Critical Reasoning

Two palaeontologists, Dr Tyson and Dr. Rees, disagree over the interpretation of certain footprints that were left among other footprints in hardened volcanic ash at site G. Dr. Tyson claims they are clearly early hominid footprints since they show human characteristics: a squarish heel and a big toe immediately adjacent to the next toe. However, since the footprints indicate that if hominids made those prints they would have had to walk in an unexpected cross-stepping manner, by placing the left foot to the right of the right foot. Dr. Rees rejects Dr. Tyson's conclusion.

Which one of the following, if true, most seriously undermines Dr. Tyson's conclusion?

(A) The foot prints showing human characteristics were clearly those of at least two distinct individuals.
(B) Certain species of bears had feet very like human feet, except that the outside toe on each foot was the biggest toe and the innermost toe was the smallest toe.
(C) Footprints shaped like a human's that do not show a cross-stepping pattern exist at site M, which is a mile away from site G, and the two sets of footprints are contemporaneous.
(D) When the moist volcanic ash became sealed under additional layers of ash before hardening, some details of some of the footprints were erased.
(E) Most of the other footprints at site G were of animals with hooves.

OA: B

I think the answer should be D because D mentions that some details of some of the footprint were erased - hence Dr. Tyson's interpretation (they are early hominid footprints) is weakened. Since the footprint is not complete in itself, it could be of any other creature/person/animal

But B only says that only certain bears had similar feet, but it in no way provides clear explanation/evidence to prove that the footprint is not of a hominid.

Please explain!

neeti2711 wrote:
I think the answer should be D because D mentions that some details of some of the footprint were erased - hence Dr. Tyson's interpretation (they are early hominid footprints) is weakened. Since the footprint is not complete in itself, it could be of any other creature/person/animal

But B only says that only certain bears had similar feet, but it in no way provides clear explanation/evidence to prove that the footprint is not of a hominid.

Please explain!

You need to understand exactly what the argument is saying before attempting the answer options.

Imagine how we walk.
When we (and other hominids) walk normally, the biggest toes will be on the inside (facing each other)and the smallest toes will be on the outside.

Here is an image to help you visualize things -
https://www.alamy.com/stock-photo-man-ma ... 97723.html

What do we know from the argument given?
1. footprints indicate a squarish heel and a big toe.

Using only this, Dr. Tyson suggests that the footprints belong to hominids.

But if this were true then -
2. they would have had to walk in an unexpected cross-stepping manner.

What does this suggest?
that the big toes were on the outside and the smallest toes were on the inside facing each other.

this is the reason why Dr. Rees rejects Dr. Tyson's conclusion.

Option B weakens Dr. Tyson's conclusion by suggesting that the footprints were not made by hominids but made by bears.
Those bears had biggest toes on the outside and their innermost toes were the smallest.

Option D is incorrect because you still KNOW these things -
"show human characteristics: a squarish heel and a big toe immediately adjacent to the next toe.".

these characteristics are enough for Dr. Tyson to draw his conclusion.

Hope this helps.