If a Biochemical Imbalance Were the Cause of a Person's

If a biochemical imbalance were the cause of a person's depression, the latest research would lead us to expect to find that person to have:

A) an abnormality in the activity of certain neurotransmitters, especially serotonin and norepinephrine.
B) especially high levels of the neurotransmitters dopamine and acetylcholine and their metabolites.
C) particularly low levels of the neurotransmitters cortisol and melatonin, as measured by their metabolites.
D) an absence of the neurotransmitters cortisol and serotonin.