In DNA, the designations 3' and 5' refer to the
a. bonds formed between phosphate groups and carbon atoms of deoxyribose.
b. carbon or nitrogen atoms on the rings of purine or pyrimidines.
c. cross-linking of the third and fifth carbon atoms of deoxyribose.
d. bonding between purines and deoxyribose and between pyrimidines and deoxyribose.
e. bonds that form between adenine and thymine and between guanine and cytosine.
Answer: A