(A) : A helical spring tends to contract, when a current passes through it
(R) : Two straight parallel metallic wires carrying current in same direction repel each other

Options

A. Both 'A' and 'R' are true and 'R' is the correct explanation of 'A'.
B. Both 'A' and 'R' are true and 'R' is not the correct explanation of 'A'
C. 'A' is true and 'R' is false
D. 'A' is false and 'R' is false

Answer

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "A helical spring tends to contract when a current passes through it."
- When a current flows through a helical spring, the spring behaves like a series of parallel wires. The current in the adjacent coils of the spring creates a magnetic field that interacts with the current in the other coils.

2. **Analyzing the Behavior of the Spring**:
- According to the principles of electromagnetism, when two parallel conductors carry current in the same direction, they attract each other.
- In the case of the helical spring, the coils are parallel to each other, and since the current flows in the same direction through adjacent coils, they will attract each other, causing the spring to contract.

3. **Conclusion on Assertion (A)**:
- Therefore, the assertion is **True**.

4. **Understanding the Reason (R)**:
- The reason states that "Two straight parallel metallic wires carrying current in the same direction repel each other."
- This statement is incorrect. In fact, two parallel wires carrying current in the same direction attract each other.

5. **Conclusion on Reason (R)**:
- Therefore, the reason is **False**.

6. **Final Evaluation**:
- Since the assertion is true and the reason is false, we conclude that the correct option is that the assertion is true, and the reason is false.

### Final Answer:
- Assertion (A) is True.
- Reason (R) is False.
- The correct option is **C**.