Which of the following is true about the structure of a double-stranded DNA molecule? 

A. The nitrogenous bases in one strand are held to the nitrogenous bases of the other strand by phosphodiester bonds.

B. Purine nucleotides always form base pairs with other purines, and pyrimidine nucleotides always form base pairs with other pyrimidines.

C. The nucleotides in a strand of DNA are held together by hydrogen bonds.

D. The diameter of a DNA molecule is the same along its entire length due to the specific complementary base pairing of the DNA nucleotides.