80. In bacteria, the biosynthetic routes for proline and arginine diverge when glutamate is N-acetylated for arginine synthesis. Which of the following explains why acetylation is required for arginine synthesis but not proline synthesis? (A) Acetylation alters the pKa of the amine group. (B) Acetylation prevents reduction of the amine group in N-acetylglutamate-δ-semialdehyde. (C) Acetylation activates tiie amine group for synthesis of the guanidine group of arginine. (D) Acetylation prevents the cyclization of N-acetylglutamate-δ-semialdehyde. (E) None of the above.