Okay, let's tackle this question. The question is about DNA proofreading and repair. Hmm, DNA replication accuracy is crucial, right? I remember that DNA polymerases have a proofreading function. So during replication, when the polymerase adds a nucleotide, if it makes a mistake, the enzyme can detect it and correct it before continuing. That's the 3' to 5' exonuclease activity.

Wait, so the question is asking which enzyme or process is responsible for proofreading and repair. The options aren't filled in, but the correct answer is probably DNA polymerase. Let me think. DNA polymerase has both the polymerase activity and the proofreading exonuclease activity. Other enzymes like DNA ligase are involved in joining strands, not proofreading. DNA helicase unwinds the strands. DNA gyrase deals with supercoiling. So the correct answer should be DNA polymerase.

Now, the wrong options might be other enzymes. For example, DNA ligase is involved in sealing nicks, not proofreading. DNA helicase is part of the replication machinery but doesn't do proofreading. DNA topoisomerase helps with supercoiling. So each of these is a distractor. The clinical pearl here is that DNA polymerase's proofreading function is key to minimizing replication errors, which is why mutations are less common. If the question's correct answer is DNA polymerase, then the explanation would highlight its 3' to 5' exonuclease activity. I need to make sure I cover all the sections: core concept, why correct, why wrong options are wrong, a clinical pearl, and then the correct answer line. Let me structure the explanation accordingly.

**Core Concept**
DNA proofreading and repair during replication are primarily managed by **DNA polymerase**, which uses its **3'→5' exonuclease activity** to detect and correct mismatched nucleotides. This proofreading function significantly reduces replication errors, ensuring genomic fidelity.

**Why the Correct Answer is Right**
DNA polymerase III (in prokaryotes) and DNA polymerase ε (in eukaryotes) possess intrinsic proofreading capabilities. When an incorrect nucleotide is incorporated, the enzyme reverses direction (due to its exonuclease domain), removes the mismatched base, and resumes synthesis. This mechanism reduces error rates to ~1 in 10^9–10^10 bases. Post-replication repair mechanisms like mismatch repair (MMR) further correct residual errors but are distinct from polymerase-driven proofreading.

**Why Each Wrong Option is Incorrect**
**Option A:** DNA ligase seals nicks in the DNA backbone during replication/repair but does not proofread.
**Option B:** DNA helicase unwinds the DNA double helix for replication but lacks proofreading activity.
**Option C:** DNA topoisomerase relieves torsional strain but is unrelated to proofreading.

**Clinical Pearl / High-Yield Fact**
DNA polymerase’s proofreading function is a **high-yield exam topic**; mutations in proofreading enzymes (e.g., *POLE* in humans) are linked to cancer due to increased mutagenesis. Remember: **"Polymerase proofreads, ligase ligates"** to distinguish roles.

**Correct Answer: C. DNA Polymerase**

✓ Correct Answer: A. DNA polymerase