16. The double helix of DNA in the B-form is stabilized mostly by:
(A) hydrogen bonds between the riboses of each strand.
(B) ribose interactions with the planar base pairs.
(C) nonspecific base-stacking interaction between two adjacent bases in the same strand.
(D) hydrogen bonding between the phosphate groups of two side-by-side strands.
(E) covalent bonds between the 3' end of one strand and the 5' end of the other.