The correct option is C
Abu Bakr's empire controlled the three most sacred sites in Islam.
The three most sacred sites in Islam are Kaaba and Al-Masjid al-Haram, Mecca, Saudi Arabia and Al-Masjid an-Nabawi in Medina, Saudi Arabia as well as Al-Aqsa Mosque, Jerusalem. Abu Bakr had been a close confidant of Muhammad, and expanded the caliphates a great deal.