In the Human Genetic Disease Maple Syrup Urine Disease, the Metabolic

In the human genetic disease maple syrup urine disease, the metabolic defect involves:

A) a deficiency of the vitamin niacin.
B) oxidative decarboxylation.
C) synthesis of branched chain amino acids.
D) transamination of an amino acid.
E) uptake of branched chain amino acids into liver.