A. Umar ibn al-Khattab
B. Ali ibn Abi Talib
C. Uthman ibn Affan
D. Abu Bakr al-Siddiq
Answer: Umar ibn al-Khattab
Who was the famous Muslim caliph known for his military conquests and the expansion of the Islamic Empire?
Additional Information: Umar ibn al-Khattab was known for his military conquests and significantly expanding the Islamic Empire during his caliphate.
Subjects: Famous Islamic Personalities, Islamiyat