Critical Reasoning

Which of the following most logically completes the argument?

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that,in test-tube solutions, renders these metals chemically inert. Possibly, therefore, the herb's high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

A. histidine is found in all parts of the plant-roots, stem, leaves, and flowers
B. the herb's high level of histidine production is found to be associated with an unusually low level of production of other amino acids
C. others of the closely related group of plants are also found to produce histidine in large quantities
D. cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic
E. the concentration of histidine in the growing herb declines as the plant approaches maturity

Answer should be C:

The stem mentions that this herb(say X) is part of a group of plants and all the plants in that group can thrive in soil with high concentration of metals that are toxic to most other plants,

If say, other plants in the group are not found to contain large amounts of histidine,then the reason this group of plants(including X) can thrive in such soils is something other than histadine

need720+ wrote:Which of the following most logically completes the argument?

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants. Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that,in test-tube solutions, renders these metals chemically inert. Possibly, therefore, the herb's high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

A. histidine is found in all parts of the plant-roots, stem, leaves, and flowers
B. the herb's high level of histidine production is found to be associated with an unusually low level of production of other amino acids
C. others of the closely related group of plants are also found to produce histidine in large quantities
D. cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic
E. the concentration of histidine in the growing herb declines as the plant approaches maturity

IMO D

if in long run the cultivation of herb makes the metals chemically inert , then it means histidine is effective

C - weaken the argument

I will go with E here.

Conclusion : High Histidine production allows plant to grow in metal-rich soils. => Only purpose of histidine is to allow the plant to grow in the metal-rich soil.

E states that as the plant continues its growth, the histidine production declines => In effect, indicating that indeed histidine just allows the plant to start growing in metal-rich soil.

Crick

D is my response.

It is saying H allows plants to grow in metal/toxic areas.

If this is true, then D can be used as a premise.

All feedback appreciated.

Answer will definitely be [spoiler]"C".[/spoiler]

If my answer is correct, I will write down my explanation. Anyway - very nice Question.

IMO D.

Definitely E ..
This proves that Histidin is essential for the growth of plants. The level of histidine will drop once the plant approaches its maturity; hence, less histidine will be required for the plant to grow.

This is a poorly constructed question from the GMAC banned resource - scoretop sets. Stay away !!

D is what i feel
OA please...!!!

According to me it gt to be D

IMO its E coz it supports the conclusion.

IMO:C !

bblast wrote:This is a poorly constructed question from the GMAC banned resource - scoretop sets. Stay away !!

Why did GMAC ban scoretop sets ? I dont think the reason warrants our staying away from this source .

However i hate this question i can try to justify all the choices C , D and E .
why did someone who liked this CR like this CR ?