Okazaki fragments are best described as:

• A. The continuous segments on the leading strand
• B. The RNA primers on the lagging strand
• C. The enzymes that unwind DNA
• D. Discontinuous DNA segments on the lagging strand

Answer: (D)

Okazaki fragments show how the lagging strand is synthesized in short, discontinuous segments. During DNA replication, the two strands are made in opposite directions; the leading strand is built continuously toward the fork, while the lagging strand is synthesized in small pieces called Okazaki fragments. Each fragment starts with an RNA primer, but the fragment itself is DNA, and the RNA primers are later removed and replaced with DNA and the fragments joined by DNA ligase to form a continuous strand. So this concept is best described as discontinuous DNA segments on the lagging strand, rather than continuous segments on the leading strand, RNA primers themselves, or enzymes that unwind DNA.