Charlie Is a Hypochondriac

Charlie is a hypochondriac. He's always worried he has something. Is that cough an early sign of lung cancer? He's thirsty; is it diabetes? He can't shake hands because he might pick up flu germs. He disinfects everything. Yet, despite his almost obsessive precautions, he comes down with one bug after another. Can you give a plausible explanation?

A) He's just imagining that he is sick.
B) The cough indicates that he is probably diabetic and that makes him susceptible to illness.
C) Charlie is producing too much growth hormone, which is exhausting his system.
D) Stress releases cortisol, and cortisol suppresses the immune system.
E) Charlie has a goiter, which is increasing his immune response.