24. To determine the isoelectric point of a protein, first establish that a gel: (A) contains a denaturing detergent that can distribute uniform negative charges over the protein's surface. (B) exhibits a stable pH gradient when ampholytes become distributed in an electric field. (C) is washed with an antibody specific to the protein of interest. (D) neutralizes all ionic groups on a protein by titrating them with strong bases. (E) relates the unknown protein to a series of protein markers with known molecular weights, Mr.