The Bases of Nucleic Acids Are Purines or Pyrimidines

The bases of nucleic acids are purines or pyrimidines. Purines and pyrimidines are distinguished by the fact that

A) purines include the bases of cytosine and thymine; pyrimidines include the bases of adenine and guanine.
B) pyrimidines are found in RNA; purines are found in DNA.
C) purines consist of hydrogen, carbon, oxygen, and nitrogen, whereas pyrimidines have phosphorus, hydrogen, carbon, oxygen, and nitrogen.
D) purines only have single bonds in their structure, whereas pyrimidines have both single and double bonds in their structure.
E) purines are double-ring structures, whereas pyrimidines are single-ring structures.