The Monoamine Hypothesis of the Development of Depression Focuses on Insufficient

The monoamine hypothesis of the development of depression focuses on insufficient activity of several neurotransmitters. Although this hypothesis has influenced treatment, it is not without shortcomings as an explanation for depression. What is one of the problems of this hypothesis?

A) In some cases, high levels of these neurotransmitters are the actual cause of depression.
B) Not all people who suffer depression have all the neurotransmitters thought to be involved in depression.
C) Other neurotransmitters such as GABA and acetylcholine appear to be involved in some cases of depression.
D) The neurotransmitter levels thought to be involved in depression are actually responding to changes in diet that often accompany depression.