这道逻辑 为什么是E 不是C呢

bernadotte

Q28:

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.  ossibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

1. histidine is found in all parts of the plant—roots, stem, leaves, and flowers
   
   
   
2. the herb’s high level of histidine production is found to be associated with an unusually low level of production of other amino acids
   
   
   
3. others of the closely related group of plants are also found to produce histidine in large quantities
   
   
   
4. 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
   
   
   
5. the concentration of histidine in the growing herb declines as the plant approaches maturity
   
   
   

edwardelric

E说随着H的生长，H减少了，直到herb成熟。（这不是不用加东西么herb生长他分泌H，herb不生长他不分泌H.不是什么东西都不用加么最直接）
Ｃ说和herb相近的那些植物都分泌大量的H 对题目没有什么帮助