A protein has an isoelectric point (pI) of 9. Which of the following statements best describes the state of this protein in aqueous solution at pH 7? A. The side chains of the protein's basic residues will be mostly uncharged
B. The side chains of the protein's acidic residues will be mostly protonated
C. The protein will have no net charge
D. The protein will have a net positive charge
E. The protein will have a net negative charge