A Group of Researchers Is Looking at How Catecholamine Production

A group of researchers is looking at how catecholamine production is regulated in response to extreme stress. Subject rats are randomly allocated to either an experimental or a control group in the experiments. The pituitary gland is resected in the experimental rats, while the control rats get a craniotomy without pituitary resection. When compared to control animals, the experimental animals produce less epinephrine from the adrenal medulla and less cortisol from the adrenal cortex. Which of the following enzymes' decreased activity is most likely responsible for the reduced epinephrine levels in the experimental animals?

A) Catechol-O-methyl transferase
B) Dopa decarboxylase
C) Dopamine beta-hydroxylase
D) Monoamine oxidase
E) Phenylalanine hydroxylase
F) Phenylethanolamine-N-methyltransferase
G) Tyrosine hydroxylase