血液是人体的一种重要组织，它具有多方面的重要作用。

血液中的葡萄糖是重要的供能物质，维持血糖含量相对稳定的激素主要是（）等。科学家通过研究发现，把摄取糖与声音刺激多次结合以后，单独的声音刺激也能引起几乎与摄取糖时同样的血糖含量变化，这说明了在糖代谢中具有主导作用的高级神经中枢是在（）。

A study comparing a group of chronically depressed individuals with an otherwise matched group of individuals free from depression found significantly more disorders of the immune system among the depressed group. According to the researchers, these results ply support the hypothesis that mental states influence the body’s vulnerability to infection. Which of the following, if true, casts the most serious doubt on the researchers’ interpretation of their findings

A．The researchers’ view does little more than echo a familiar theme in folklore and literature.

B．Chronically depressed individuals are no less careful than others to avoid exposure to infections.

C．Disorders of the immune system cause many of those individuals who have them to become chronically depressed.

D．Individuals who have previously been free from depression can become depressed quite suddenly.

E．(E) A high frequency of infections can stem from an unusually high level of exposure rater than from any disorder of the immune system.