Final answer:
Option B, 'Forms a double-helix,' is NOT descriptive of both DNA and RNA, as RNA typically does not form a double helix like DNA does.
Step-by-step explanation:
Among the options provided, the statement that is NOT descriptive of both DNA and RNA is B. Forms a double-helix. DNA is well-known for its double-helical structure in which two strands wind around each other. RNA, on the other hand, is typically single-stranded and does not form a double helix. While both DNA and RNA are composed of nucleotides, which include a phosphate group, a sugar, and a nitrogenous base, RNA's sugar is ribose rather than the deoxyribose in DNA. Moreover, RNA features uracil in place of thymine, which is present in DNA.
DNA and RNA both have a backbone made up of a sugar and phosphate, and they each contain four different types of nitrogen bases. However, the nitrogen bases in RNA are adenine (A), cytosine (C), guanine (G), and uracil (U) instead of thymine (T), which is found in DNA. Both DNA and RNA are indeed made up of nucleotides, confirming options A, C, and D as descriptive of both DNA and RNA.