The tension in the DNA strands created by unwinding of DNA is release by:
a) DNA polymerase II
b) DNA polymerase III
c) Helicase
d) Topoisomerase

Options

A. DNA polymerase II
B. DNA polymerase III
C. Helicase
D. Topoisomerase

Explanation

To solve the question regarding which enzyme releases the tension in the DNA strands created by unwinding, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is a double-stranded helix, and during processes like replication, the strands need to be unwound to allow access to the genetic information.

2. **Identifying the Problem**:
- When the DNA strands are unwound, it creates tension in the form of supercoiling ahead of the replication fork. This tension needs to be relieved to prevent the DNA from becoming too tightly coiled.

3. **Role of Enzymes in DNA Replication**:
- Several enzymes are involved in DNA replication:
- **DNA Polymerase II**: Involved in DNA repair and replication.
- **DNA Polymerase III**: The primary enzyme for DNA replication in prokaryotes.
- **Helicase**: Unwinds the DNA double helix, creating the replication fork.

4. **Identifying the Correct Enzyme**:
- While helicase unwinds the DNA, it does not relieve the tension created by this unwinding. The enzyme responsible for relieving this tension is **Topoisomerase**. Topoisomerase works by cutting the DNA strands, allowing them to unwind and then rejoining them, thus relieving the tension.

5. **Conclusion**:
- Based on the roles of the enzymes discussed, the correct answer to the question is **Topoisomerase (d)**.

### Final Answer:
**d) Topoisomerase**

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