In the Watson-Crick Model of DNA Structure:
A) Both Strands $\rightarrow$

In the Watson-Crick model of DNA structure:

A) both strands run in the same direction, 3' $\rightarrow$ 5'; they are parallel.
B) phosphate groups project toward the middle of the helix, where they are protected from interaction with water.
C) T can form three hydrogen bonds with either G or C in the opposite strand.
D) the distance between the sugar backbone of the two strands is just large enough to accommodate either two purines or two pyrimidines.
E) the distance between two adjacent bases in one strand is about 3.4 Å.