Final answer:
Proofreading by DNA polymerase involves exonuclease activity to remove incorrect basepairs and ultimately increases the accuracy of DNA replication; hence, all options (A), (B), and (C) are correct.
Step-by-step explanation:
Proofreading by DNA polymerase is a crucial mechanism during DNA replication that ensures the accuracy of the genetic code. This process involves several key steps:
- (A) The proofreading occurs thanks to the exonuclease activity of DNA polymerase, which can remove incorrectly paired nucleotides.
- (B) Proofreading also removes incorrect basepairs that have been incorporated into the growing DNA strand.
- (C) Ultimately, this proofreading function increases the accuracy of replication by correcting these mistakes.
Therefore, the correct answer to the question is (D) All of the above, as proofreading by DNA polymerase covers all these aspects to maintain the fidelity of DNA replication.