Caspi and Colleagues Found That

Caspi and colleagues found that

A) depression is caused by too much serotonin.
B) when exposed to stressful life events, persons with two long alleles (LL) for 5-Htt were at the highest risk for depression.
C) when exposed to stressful life events, persons with a long and a short allele (Ls) for 5-Htt were at the highest risk for depression.
D) when exposed to stressful life events, persons with two short alleles (SS) for 5-Htt were at the highest risk for depression.