Assertion: Both rhombic and monoclinic sulphur exist as S8 but oxygen exists as O2.

Reason: Oxygen forms  multiple bonds due to its small size and small bond length but  bonding is not possible in sulphur.

1. Both the assertion and the reason are correct statements and the reason is the correct explanation of the Assertion.

2. Both Assertion and Reason are correct statements, and Reason is not the correct explanation of the Assertion.

3. The assertion is correct but the reason is the wrong statement.

4. Both the assertion and the reason are wrong statements.

HINT: Oxygen can form $\mathrm{\pi }$ bonds due to its small size but sulphur cannot form.
Explanation:
Both rhombic and monoclinic sulphur exists as S8 but oxygen exists as O2, because oxygen forms  multiple bonds
due to it's small size and small bond length.
But  bonding is not possible in sulphur due to its bigger size as compared to oxygen.
The structures of Sand O2 are as follows: