In the metabolic pathway for the synthesis of valine, leucine, and isoleucine, what are the initial reactants and their origins?

• A. Pyruvate and Acetyl-CoA; Glycolysis and Citric Acid Cycle
• B. Glucose-6-phosphate and Fructose-6-phosphate; Glycolysis
• C. Ribose 5-phosphate and PEP; Pentose Phosphate Pathway and Glycolysis
• D. Oxaloacetate and Alpha-ketoglutarate; Citric Acid Cycle

Answer: (A)