A : It has been predicted that a global nuclear war on the earth would be followed by a severe 'nuclear winter' with a devastating effect on life on earth.
R : The clouds produced by global nuclear war would perhaps cover substantial parts of the sky preventing solar light from reaching many parts of the globe causing winter.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion (A)**: The assertion states that a global nuclear war would lead to a severe 'nuclear winter' with devastating effects on life on Earth. This means that the aftermath of such a war would drastically alter the climate, making it significantly colder.

2. **Understanding the Reason (R)**: The reason provided explains that the clouds produced as a result of a global nuclear war would cover substantial parts of the sky. This cloud cover would prevent solar light from reaching many areas of the Earth, which is a key factor in causing the winter-like conditions.

3. **Linking Assertion and Reason**: The assertion and reason are closely linked. The clouds produced by the nuclear explosions would indeed block sunlight, leading to a drop in temperatures. This phenomenon is what is referred to as 'nuclear winter'.

4. **Conclusion**: Both the assertion and the reason are correct and they are related to each other. The assertion accurately predicts the occurrence of a nuclear winter following a nuclear war, and the reason provides a valid explanation for how this would happen.

5. **Final Answer**: Therefore, the correct conclusion is that both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion. Thus, option 1 is the correct answer.

---