Question

what is the role of dna ligase in the elongation of the lagging strand during dna replication?
it synthesizes rna nucleotides to make a primer.
it joins okazaki fragments together.
it unwinds the parental double helix.
it catalyzes the lengthening of telomeres.

Explanation:

DNA ligase is an enzyme. During DNA replication, on the lagging strand, DNA is synthesized in short fragments called Okazaki fragments. DNA ligase functions to form phosphodiester bonds between these Okazaki fragments, effectively joining them together to create a continuous strand.
Synthesizing RNA nucleotides to make a primer is the role of primase. Unwinding the parental double helix is done by helicase. Catalyzing the lengthening of telomeres is the job of telomerase.

Answer:

It joins Okazaki fragments together.