A: During evolution the early time period was without ozone layer.
R: Ozone layer absorbs U.V. rays to some extent.

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 falses statements, then mark (4)

Answer

To solve the assertion and reason question, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
**Assertion (A)**: During evolution, the early time period was without an ozone layer.

- This statement is correct. The early Earth lacked free oxygen, which is essential for the formation of ozone (O3). Ozone is formed when free oxygen (O2) interacts with ultraviolet (UV) light, creating ozone molecules. In the primitive atmosphere, the absence of free oxygen meant that the ozone layer could not form.

### Step 2: Analyze the Reason
**Reason (R)**: Ozone layer absorbs U.V. rays to some extent.

- This statement is also correct. The ozone layer acts as a protective shield that absorbs a significant portion of the Sun's harmful ultraviolet radiation. This absorption is crucial for protecting living organisms from the damaging effects of UV rays, which can cause mutations and other harmful effects.

### Step 3: Determine the Relationship
- While both the assertion and reason are true, the reason does not explain why the assertion is true. The assertion discusses the absence of the ozone layer during early evolution due to a lack of free oxygen, while the reason explains the function of the ozone layer, which is unrelated to the absence of it during that time.

### Conclusion
- Therefore, both statements are correct, but the reason is not a correct explanation of the assertion. The correct answer is option 2.

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