Research Involving Treatments That Induce Acute Tryptophan Depletion in the Brain

Research involving treatments that induce acute tryptophan depletion in the brain have found that this type of treatment

A) often induces the core symptoms of depression in normal, healthy humans.
B) often induces symptoms of depression in individuals who have a family history of major depression
C) often reduces the symptoms of depression in individuals diagnosed with major depression
D) both a and b