Statements: (1) In the tripeptide Gly-Ala-Ser, the amino acid at the N-terminal end is Ser. (2) More than one polypeptide chain may be present in a conjugated protein but not in a simple protein. (3) In solution at physiological pH, the side chain of a polar basic amino acid bears a negative charge. a. All three statements are true. b. Two of the three statements are true. c. Only one of the statements is true. d. None of the statements are true.