Answer: The answer is by the Angel Gabriel appearing to him in a cave on Mount Hira.
Step-by-step explanation:
How though?
How was the Qur'an revealed to Muhammad? The Qur'an was revealed to Muhammad by the Angel Gabriel appearing to him in a cave on Mount Hira. The angel spoke to Muhammad and Muhammad began reciting the words from God.
How the Quran was revealed and compiled?
It was collected and made into a book by the first Caliph; or by the second; or by the third, Uthman