Answer: Father-in-law of Prophet Muhammad Abu Bakr became the first caliph after his death.
Step-by-step explanation: After the demise of Prophet, people felt that the caliphate should be in hands of such a person who has the same potential for becoming a leader as that of Prophet. Abu Bakr was the first man who accepted Islam and was really close friend of Prophet. During last days of Prophet's life, he was chosen by Prophet to lead the prayer for him. He was a man of intellect, thus he was capable of handling a state after the demise of great leader Muhammad.