Which Statement Is NOT a Similarity in the Synthesis of Isoleucine

Which statement is NOT a similarity in the synthesis of isoleucine, valine, and leucine?

A) Pyruvate is the starting compound for synthesis of all these amino acids.
B) Pyridoxal phosphate is a required cofactor in the synthesis of all these amino acids.
C) These are all essential amino acids in humans.
D) An $\alpha$ -keto acid is the immediate precursor for all three synthetic pathways.
E) Acetyl-CoA is required as a substrate in all three synthetic pathways.