An enzyme catalysing the removal of nucleotides from the ends of DNA is

Options

A. a) endonuclease
B. b) exonuclease
C. c) DNA ligase
D. d) Hind ll

Explanation

To solve the question about which enzyme catalyzes the removal of nucleotides from the ends of DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for an enzyme that removes nucleotides specifically from the ends of DNA.

2. **Identify the Options**: The options given are:
- A) Endonuclease
- B) Exonuclease
- C) DNA ligase
- D) Hind III

3. **Analyze Option A - Endonuclease**:
- Endonucleases are enzymes that cut DNA at specific internal sites, not at the ends. Therefore, they do not remove nucleotides from the ends of DNA.
- **Conclusion**: This option is incorrect.

4. **Analyze Option B - Exonuclease**:
- Exonucleases are enzymes that remove nucleotides from the ends of DNA. They can act on either the 5' or 3' ends of the DNA strand.
- **Conclusion**: This option is correct.

5. **Analyze Option C - DNA Ligase**:
- DNA ligase is an enzyme that joins DNA fragments together. It does not remove nucleotides; rather, it facilitates the joining of DNA strands.
- **Conclusion**: This option is incorrect.

6. **Analyze Option D - Hind III**:
- Hind III is a specific type of endonuclease that cuts DNA at specific internal sites. It does not remove nucleotides from the ends of DNA.
- **Conclusion**: This option is incorrect.

7. **Final Conclusion**: The enzyme that catalyzes the removal of nucleotides from the ends of DNA is **Exonuclease** (Option B).

### Final Answer:
The correct answer is **B) Exonuclease**.