Considering the diagrams below that show hydrogen-bond donors and acceptors as well as hydrophobic groups in four DNA base pairs, which of the following do you think is the most difficult to accomplish by DNA-binding proteins?

A) Distinguishing between A-T and T-A in the major groove
B) Distinguishing between A-T and C-G in the major groove
C) Distinguishing between C-G and G-C in the major groove
D) Distinguishing between C-G and G-C in the minor groove
E) Distinguishing between C-G and T-A in the minor groove