At a PH of 4.0,the

At a pH of 4.0,the:

A) carboxyl and amino groups of an amino acid become unprotonated,causing the amino acid to have a net negative charge.
B) carboxyl and amino groups of an amino acid become protonated,causing the amino acid to have a net positive charge.
C) carboxyl group of an amino acid is dissociated and the amino group is protonated,giving the amino acid no net charge.
D) amino group of an amino acid is dissociated and the carboxyl group is protonated,giving the amino acid no net charge.