DNA ligase is an enzyme that catalyses the

Options

A. Splitting of DNA threads into small bits
B. Joining of the fragments of DNA
C. Denaturation of DNA
D. Synthesis of DNA

Answer

**Step-by-Step Solution:**

1. **Understand the Role of DNA Ligase**: DNA ligase is an enzyme that plays a crucial role in molecular biology. Its primary function is to join DNA fragments together.

2. **Evaluate the Options**:
- **Option A**: Splitting of DNA threads into small bits. This is incorrect because DNA ligase does not split DNA; it joins fragments.
- **Option B**: Joining of the fragments of DNA. This is correct as DNA ligase catalyzes the joining of DNA fragments.
- **Option C**: Denaturation of DNA. This is incorrect. Denaturation refers to the loss of the DNA's natural structure, typically due to heat, and is not a function of DNA ligase.
- **Option D**: Synthesis of DNA. This is also incorrect because DNA synthesis is primarily carried out by DNA polymerases, not DNA ligase.

3. **Select the Correct Answer**: Based on the evaluation of the options, the correct answer is **Option B**: joining of the fragments of DNA.

4. **Conclusion**: DNA ligase is an enzyme that catalyzes the joining of DNA fragments, making Option B the correct choice.

---