After Abu Bakr succeeded Muhammad, how did he unite Arabia and its surrounding territories?
A. by strengthening alliances with Bedouin tribes
B. by gaining the loyalty of Muhammad's son-in-law Ali
C. by convincing others that he was a divine ruler
D. by promising religious freedom to everyone
The best answer to this question is Option A. The major thing that Abu Bakr had to do in order to allow Islam to spread was to regain control over the tribes of Arabia. After the death of Muhammad, the tribes had, in a sense, rebelled. They argued that their only loyalty was to Muhammad himself and that they should not have to be ruled by Abu Bakr. Abu Bakr defeated them in battle and then strengthened ties with them. This united Arabia and allowed Islam to then spread to the surrounding areas.
You could make a case for Option B. There was some degree of conflict between Abu Bakr and Ali over who should succeed Muhammad. If Ali had chosen to fight Abu Bakr, it might have caused a major rift among the Muslims. You could say that Ali allowed Islam to spread by accepting Abu Bakr’s rule. It might be wise to check and see which option your text says is correct.
Neither of the other options is plausible. Muslims do not believe in the divinity of any human beings. While they were not religiously intolerant, toleration was not their main way of spreading their rule. Thus, I would choose Option A, though a case can be made for Option B.