Final answer:
The correct option in the final answer is D. DNA polymerase is the enzyme responsible for DNA replication in the nucleus of a cell, adding nucleotides to the growing chain and proofreading to minimize errors.
Step-by-step explanation:
The enzyme responsible for replication in the nucleus of a cell is DNA polymerase. This enzyme plays a critical role in DNA replication by adding nucleotides one by one to the growing DNA chain that is complementary to the template strand. During this process, DNA polymerase requires a template strand against which to synthesize a new strand, and it adds new DNA to the 3' end of the pre-existing chain in successive condensation reactions, which requires energy obtained from triphosphate nucleotides.
The action of DNA polymerase is not without checks, as it also exhibits proofreading abilities to ensure the fidelity of DNA replication, making errors rare events. Hence, the correct option for the enzyme responsible for replication in the nucleus of a cell is D. DNA polymerase.