Pyruvate dehydrogenase (PDH) catalyzes acetyl-CoA from pyruvate, CoA, and NAD+. Which of the following statements are correct?
a) PDH is inhibited by high levels of ATP and NADH.
b) PDH is stimulated by high levels of ADP and NAD+.
c) PDH is found only in the mitochondria.
d) PDH is involved in the citric acid cycle.