In Mice with a Knockout of the Tryptophan Hydroxylase 2

Multiple Choice

In mice with a knockout of the tryptophan hydroxylase 2 gene,

A) no serotonin can be synthesized in any part of the animal's body.
B) no pharmacological treatment has been found that is able to restore serotonin, even temporarily.
C) the circuitry of the serotonergic system (fiber innervation) is normal, despite the lack of serotonin.
D) impulsive aggression is increased compared to wild-type mice.