Isoelectric point of Amino Acids

The isoelectric point (pI) of an amino acid is the pH at which the amino acid exists in its zwitterionic form and carries no net electric charge. At this pH, the amino group is protonated, and the carboxyl group is deprotonated, leading to a molecule that has both positive and negative charges but whose overall net charge is zero. This unique state means that the amino acid is electrically neutral, which significantly affects its solubility and migration in an electric field. The isoelectric point is a critical property for the separation of amino acids and proteins in techniques such as isoelectric focusing. The isoelectric point (pI) of an amino acid is: A) The pH at which the amino acid exists predominantly as a zwitterion B) The pH at which the amino acid carries no net electric charge С) Both A and B are correct D) The pH at which the amino acid is most soluble in water