A 4-month-old child exhibited extreme tiredness, irritable moods, poor appetite, and fasting hypoglycemia associated with vomiting and muscle weakness. Blood test showed elevated levels of free fatty acids, but low levels of acylcarnitine. A muscle biopsy demonstrated a significant level of fatty acid infiltration in the cytoplasm. The most likely molecular defect in this child is in which one of the following enzymes?
MCAD Carnitine transporter Acetyl-CoA carboxylase CAT II