Which of the following is true of DNA?
A. The nucleotides in one strand are connected by hydrogen bonds.
B. A phosphate group in a nucleotide is attached to the 3′ carbon in ribose.
C. A purine always forms a complementary base pair with a pyrimidine.
D. The percentage of the purine A always equals the percentage of the purine G.
E. It is used by ribosomes for translation.
Answer: C