1. Which statement about the structure of the DNA double helix (B-form) is true? (A) The bases occupy the outer surface of the helix. (B) The two strands are parallel, both in the 5'-3' direction. (C) The sugar-phosphate backbone forms the minor groove. (D) The helical twist is left-handed in B-form DNA. (E) There are ~10.5 base pairs per turn in B-form DNA.