Assertion : The earth without its atmosphere would be inhospitably cold. Reason : All heat would escape in the absence of atmosphere .

Options

A. If both the assertion and reason are true and reason is correct explanation of the assertion .
B. If both the assertion and reason are true but reason is not a correct explanation of the assertion .
C. If the assertion is true but the reason is false.
D. If both assertion and reason are false.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "The earth without its atmosphere would be inhospitably cold." This means that if Earth did not have an atmosphere, its surface temperature would drop significantly, making it uninhabitable for life as we know it.

2. **Understanding the Reason**: The reason given is that "All heat would escape in the absence of atmosphere." This implies that the atmosphere plays a crucial role in retaining heat that is generated by the Earth. Without it, the heat would not be trapped and would dissipate into space.

3. **Heat Retention Mechanism**: When the Earth absorbs sunlight, it warms up. The atmosphere acts like a blanket, preventing some of this heat from escaping back into space. This is due to the greenhouse effect, where certain gases in the atmosphere trap heat.

4. **Consequences of Absence of Atmosphere**: If there were no atmosphere, the heat generated by the Earth would escape into space without any obstruction. This would lead to a significant drop in temperature, making the Earth extremely cold and inhospitable.

5. **Conclusion**: Both the assertion and the reason are correct. The assertion accurately describes the condition of Earth without an atmosphere, and the reason provides a valid explanation for why that condition would occur. Therefore, the correct answer is that both the assertion and reason are true, and the reason correctly explains the assertion.

**Final Answer**: Both Assertion and Reason are true, and the Reason correctly explains the Assertion.

---