In which domain of organisms are DNA polymerases I, II and III present?

• A. Prokaryotes
• B. Eukaryotes
• C. Archaea
• D. Viruses

Answer: (A)

Understanding how DNA replication enzymes differ among organisms helps explain why this trio points to prokaryotes. In bacteria, the replicative workhorse is DNA polymerase III, which builds the new DNA strands. DNA polymerase I then handles removing RNA primers used to start synthesis and fills in the resulting gaps with DNA. DNA polymerase II mainly participates in DNA repair and can act as a backup polymerase when needed. In contrast, eukaryotes use different polymerases for replication (such as alpha, delta, and epsilon) and mitochondria (gamma), and archaea rely on their own distinct polymerases. So, the presence of DNA polymerases I, II, and III reflects the bacterial (prokaryotic) replication system, making prokaryotes the best answer.