The correct option is A Abubakr
Abubakr was the first Caliph. Abubakr was a companion and a father-in-law of the Islamic prophet Muhammad, as well as the first of the Rashidun Caliphs. Abu Bakr is remembered as the first of the four so-called 'rightly guided' caliphs. After Muhammad's death, Abu Bakr was accepted as the first "deputy of the Prophet of God," or caliph.