Feedback Inhibition Can Be Observed in the Synthesis of Norepinephrine $\beta$

Feedback inhibition can be observed in the synthesis of norepinephrine through the

A) inhibition of tyrosine hydroxylase by norepinephrine.
B) degradation of dopamine by DOPAC.
C) availability of dopamine $\beta$ -hydroxylase.
D) inhibition of AAAD by DOPA.
E) synthesis of norepinephrine by dopamine $\beta$ -hydroxylase.