Final answer:
DNA ligase is not involved in the initiation of replication but rather joins the Okazaki fragments during the elongation and termination phases.
Step-by-step explanation:
The correct answer to the student's question is d) DNA ligase. During the initiation of replication in DNA, several key components are assembled at the origin of replication to begin the process. DNA helicase unwinds the DNA double helix, creating two single strands that need to be copied. Primase synthesizes a short RNA primer on these strands, which provides a starting point for new DNA synthesis by DNA polymerase. The RNA primer is necessary because DNA polymerases can only add nucleotides to an existing strand of DNA; they cannot start synthesizing from scratch. Conversely, DNA ligase is not involved in the initiation of replication. Instead, its role comes later in the process, where it joins the Okazaki fragments on the lagging strand to create a continuous DNA molecule, which is part of the elongation and termination phases of DNA replication.