Final answer:
The enzyme responsible for sealing the nicks between Okazaki fragments is DNA ligase.
Step-by-step explanation:
The enzyme responsible for sealing the nicks between Okazaki fragments is DNA ligase. DNA ligase is an enzyme that forms phosphodiester bonds between the adjacent nucleotides of DNA strands. It plays a crucial role in joining together the short fragments of DNA, known as Okazaki fragments, that are synthesized on the lagging strand during DNA replication.