Correct Answer: Option C — Associating partners with Allah
Explanation:
Shirk refers to the act of associating partners with Allah or attributing divine qualities to others besides Allah. It is considered the greatest sin in Islam. The Quran states in Surah An-Nisa (4:48) that Allah does not forgive Shirk but may forgive all other sins. Shirk is the opposite of Tawheed the core principle of Islamic monotheism.