Critical Reasoning

Whales originated in the freshwater lakes and rivers of ancient Asia about sixty
million years ago. Not until about ten million years later did species of whales
develop specialized kidneys enabling them to drink salt water. Although fossil
evidence shows that some early whale species that lacked such kidneys sometimes
swam in the Earth's saltwater oceans, these species must have had to return frequently
to freshwater rivers to drink.
Which of the following is most strongly supported by the information given?
A. Fossils of whale species dating from between sixty million and fifty million
years ago will not be found on continents that were at the time separated from
ancient Asia by wide expanses of ocean.
B. Among whale fossils that date from later than about fifty million years ago,
none are fossils of whale species that drank only fresh water.
C. Fossils of whale species that drank fresh water will not be found in close
proximity to fossils of whale species that drank salt water.
D. The earliest whales that drank salt water differed from fresh-water-drinking
whales only in their possession of specialized kidneys.
E. Between sixty million and fifty million years ago, the freshwater lakes and
rivers in which whales originated were gradually invaded by salt water.
[spoiler]ANS: A/C[/spoiler]

Is the OA A

I missed a point .... that whales originated in Asia. Asia and other continents were separated by vast oceans...
Hence would go for A

Even though A and C both infer too much. I think it should be A.

maihuna wrote:Whales originated in the freshwater lakes and rivers of ancient Asia about sixty
million years ago. Not until about ten million years later did species of whales
develop specialized kidneys enabling them to drink salt water. Although fossil
evidence shows that some early whale species that lacked such kidneys sometimes
swam in the Earth's saltwater oceans, these species must have had to return frequently
to freshwater rivers to drink.
Which of the following is most strongly supported by the information given?
A. Fossils of whale species dating from between sixty million and fifty million
years ago will not be found on continents that were at the time separated from
ancient Asia by wide expanses of ocean.
B. Among whale fossils that date from later than about fifty million years ago,
none are fossils of whale species that drank only fresh water.
C. Fossils of whale species that drank fresh water will not be found in close
proximity to fossils of whale species that drank salt water.
D. The earliest whales that drank salt water differed from fresh-water-drinking
whales only in their possession of specialized kidneys.
E. Between sixty million and fifty million years ago, the freshwater lakes and
rivers in which whales originated were gradually invaded by salt water.
[spoiler]ANS: A/C[/spoiler]

OA kya hain ?

mmslf75 wrote:

OA kya hain ?[/quote]

OA A:

maihuna wrote:

mmslf75 wrote:

OA kya hain ?

OA A:[/quote]


mahi,
please explain why A ?

mmslf75 wrote:

maihuna wrote:

mmslf75 wrote:

OA kya hain ?

OA A:

mahi,
please explain why A ?[/quote]
Ok, here it goes, and remember it is an gmatprep Q now with confirmed OA A, so explanation may be poor but answer will be A only.

Idea is whale originated 60 million years in fresh water lakes or rivers, and took 10 million years to develop kidneys using which they may survive in salty water, but they must frequently needed to return to freshwater lakes, so given that without such kidneys the whales can not survive for long in salty water, it means they can not go far away from fresh water sources, and so the option A that says:
Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean.

Yes agreed not the best of the choices but it is isn't?

Guys dont you think that A is too much inference here....

Please share your thoughts on this one

Let me see if i can explain this one

e-->no info is given about the gradual invasion by salt water

d-->use of only makes it a extreme choice so out

c-->this can also be infered

b-->dont know how to reason this one

a-->This means that whales didn't travel far in "wide expanses of ocean" so whales remained in close proximity to fresh water lakes

Pleaes share your thoughts on my reasoning and help me understand the gaps

Cheers!

I cant understand the exact meaning of Option A

If OA is A...wats wrong with option C

Experts please help us.

Received a PM.

This is an inference question. You need to select the best answer based on the information in the text.

The argument goes as follows:
- whales are originally from Asian fresh waters from around 60 million years ago
- they developed special kidneys to enable them to drink salt water around 50 million years ago
- even though some whales were swimming in salt waters between 60 mil and 50 mil, they had to return to fresh waters to drink

A is the answer choice here. It's impossible to find fossils of whales between 60 mil and 50 mil on continents separated from Asia by large strips of salt water (i.e. oceans), because the whales could not have gotten there. Think about it this way: if they need to drink only fresh water (don't have the appropriate kidneys yet), they can't travel for long without dying of thirst.

B is not necessarily true. While we are told that 'species of whales' developed the ability to drink salt water around 50 mil years ago, there is no 'all' in that phrase. Some of the species might not have developed those kidneys even after 50 mil.

C is again not necessarily true. You might think that each species spent time in its specific habitat (i.e. salt water vs. fresh water), but we are told in the text that some early whale species that drank fresh water sometimes swam in salt water. This is already a proof that the development stage of the kidney (and therefore the ability to drink salt water or fresh water) does not imply that whales spent all their time in this or that habitat. They might be moving around a bit.

D - there's actually no info to support this. What if they were of a different color? There's nothing in the text to point to the fact that they were exactly identical.

E could be a possible inference to explain why whales developed the special kidneys: they had to adapt to the changing environment. But this is not the unique explanation. There are others, such as the fact that salt waters contained more food than fresh waters. Some whales might have developed the special kidneys because of feeding needs and not necessarily because of a gradual change in their habitat.

if they need to drink only fresh water (don't have the appropriate kidneys yet), they can't travel for long without dying of thirst

=> I still don't understand. It could further be reasoned out by saying:
some dumb ones, who weren't aware of their kidney's efficiencies or weren't aware of the size of the salt-waters, went the other way & died on way and the waves landed their bodies to the other shore.

DanaJ wrote:Received a PM.

This is an inference question. You need to select the best answer based on the information in the text.

The argument goes as follows:
- whales are originally from Asian fresh waters from around 60 million years ago
- they developed special kidneys to enable them to drink salt water around 50 million years ago
- even though some whales were swimming in salt waters between 60 mil and 50 mil, they had to return to fresh waters to drink

A is the answer choice here. It's impossible to find fossils of whales between 60 mil and 50 mil on continents separated from Asia by large strips of salt water (i.e. oceans), because the whales could not have gotten there. Think about it this way: if they need to drink only fresh water (don't have the appropriate kidneys yet), they can't travel for long without dying of thirst.

A. Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean. OK - The conclusion must tie together two disparate claims: whales originated in Asia + species must have returned after swimming into salt water. This is the only conclusion that supports the authority of the claims. Take note of the "must"

B. Among whale fossils that date from later than about fifty million years ago, none are fossils of whale species that drank only fresh water. Reverse answer. This conclusion does not make sense after the premises given.

C. Fossils of whale species that drank fresh water will not be found in close proximity to fossils of whale species that drank salt water. Reverse answer. The fossils must be found in close proximity because "these species" must have had to return.

D. The earliest whales that drank salt water differed from fresh-water-drinking whales only in their possession of specialized kidneys. Could be true; shell game. It's tempting because indeed the kidneys must have been different. Even so, it need not be true. If it were true, it would need different support that what is provided.

E. Between sixty million and fifty million years ago, the freshwater lakes and rivers in which whales originated were gradually invaded by salt water. Could be true. If there freshwater lakes were not invaded by salt water, it is still possible that whale's kidney evolved because of a different cause.