A 44 year old man sustains a myocardial infarction, and is admitted to the hospital from the emergency room. Serum chemistries reveal two-fold elevation of his LDL cholesterol. He is prescribed lovastatin, which acts by inhibiting which of the following enzymes?
Acetyl-CoA carboxylase Carbamoyl phosphate synthetase I Hydroxymethylglutaryl-CoA reductase Pyruvate dehydrogenase