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
E. the concentration of histidine in the growing herb declines as the plant
This one has already been discussed in other threads with OA E. However, according to my source OA is D. And by the way, Im with C.
Actually for me, C, D and E are correct:
C.- If others of the closely related group of plants are also found to produce histidine
in large quantities, that histidine enable the plants to live with the metal.
D.- herb produces histidine, which makes metal inert, so other plants can also live there
E.- histidine enables herb to grow, wo in its maturity the concentration of histidine therefore declien.
All 3 are correct.
The conclusion is that the herb's high histidine levels allow it to grow in metal rich soils.
C is invalid because it states that other similar plants produce high histidine. But fails to mention if that quality assists their growth in metal rich soils
E is invalid because the argument mentions about high histidine production in general and not about high histidine productions at earlier stages or later stages of plant growth.
D - Though doesn't mention anything about having the soil suitable for other plants over an extended period, is the best choice among the available choices. As it says that cultivation of herb in soils with high metal concentration will make it suitable for their growth.
D is the best answer