求这道complete题解释~

frankzhiwei

Which of the followingmost logically completes the argument?
A certain cultivated herbis one of a group of closely related plants that thrive in soil with high concentrationsof metals that are toxic to most other plants. Agronomists studying the herb have discovered that it produces largeamounts of histidine, an amino acid that, in test-tube solutions, renders thesemetals chemically inert.  ossibly,therefore, the herb’s high histidine production is what allows it to grow inmetal-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 tobe associated with an unusually low level of production of other amino acids
C.     others of the closely related group of plants are alsofound to produce histidine in large quantities
D.     cultivation of the herb in soil with high concentrations ofthe metals will, over an extended period, make the soil suitable for plants towhich the metals are toxic
E.      the concentration of histidine in the growing herb declinesas the plant approaches maturity


基本没看懂，答案是C，那位能帮忙解释一下~感谢感谢！

sdcar2010

This is causation vs. correlation.  A closely related group of plants survives the high concentration of metals in soil.  The stimulus provides a hypothesis that the production of histidine in one herb from this group of plants is required for the herd to detoxify the metal.  If other plants from the same closely related group are also found to produce histidine and we already know these plants can deal with the metals, then it is more likely the stated hypothesis is right.