Concept:Umar ibn al-Khattab became a Muslim after an incident at his sister’s house.Explanation:Umar set out to harm Prophet Muhammad, but he was told that his sister and brother-in-law had accepted Islam.He went to his sister’s house and beat her because of her new faith.Seeing her firm faith, and later hearing/reading the Qur’an, he was moved and accepted Islam.Therefore, the major event in his conversion was the incident involving the beating of his sister.Answer:B. the beating of his sister