Concept:The year 610 C.E. is important in Islam because it marks the beginning of Muhammad’s (S.A.W.) prophethood through the first revelation.Explanation:While Muhammad (S.A.W.) was meditating in the cave of Hira, the Angel Jibreel appeared to him.He received the first verses of the Quran from Allah at that time.This event made 610 C.E. unforgettable because it started the divine mission of Islam.None of the other events in the options occurred in that same year.Answer:Option A — Received the first revelation.