Known as the Hijrah, Mohammed fled the city of Mecca with his followers; this event marks the beginning of the Muslim calendar.

Mohammed's birth date is celebrated in some Muslim communities as the holiday Mawlid, but it is not the beginning of the Muslim calendar.

Mohammed's death is an important event in Muslim history but not the beginning of the Muslim calendar.

The vast majority of Muslim worshippers worldwide are Sunni. They believe that Islam's first caliph was Muhammad's father-in-law Abu Bakr. This is different from the main minority denomination in Islam, Shia, who believe that Islam's first caliph was Ali ibn Abi Talib - Muhammad's cousin and son-in-law. The split in denominations occurred almost immediately after Muhammad's death, but was greatly exacerbated after the Battle of Karbala in 680. 

The Umayyad Caliphate was the second of four major Islamic caliphates established after the death of Muhammad. Although the Umayyad family was from Mecca, they established their capital in Damascus, in modern day Syria. The Umayyads continued the Muslim conquests that had begun earlier, adding territories in North Africa and stretching all the way to Al-Andalus in Spain. At its peak, the Umayyad Caliphate was the ruler of 62 million people, around 29% of the world population at the time. 

The Abbassid Caliphate overthrew the Umayyad Caliphate in 750. Although the Abbassids were also from Mecca, they established their capital in Baghdad, in modern day Iraq. Although not as expansionary as the Umayyads, the Abbassid Caliphate was renowned for advancements in culture and science during the time known as the "Islamic Golden Age" that ended when Mongol invaders sacked Baghdad in 1258.

The Quraysh were a powerful tribe that controlled Mecca at the beginning of Islamic history. Muhammad originated from this tribe, but he and his Muslim followers would later battle against them as the religion of Islam grew. The other answers are incorrect because they are either caliphates that came from the Quraysh (Abbasid, Ummayad, Fatimid), or refer to a term that means "rightly guided" (Rashidun).

The Rashidun Caliphs ruled the Muslim community in the immediate few decades following Muhammad's death. Therefore, Muhammad is the incorrect answer.

622 marks a famous year in Muslim history - one in which Muhammad left his birthplace of Mecca and fled to Medina (then referred to as Yathrib). The other answers are incorrect because they refer to other locations in the Middle East that Muhammad did not travel to.

The five pillars of Islam dictate the actions of a good practicing Muslim. Although the Qu'ran is the central text of the religion, reading it is not counted among the five pillars - thus "Q'ara" (To read) is the correct answer.

The prophet Muhammad was born in Mecca. Muslims believe the Quran derived from revelations given to Muhammad from the angel Gabriel. As he gained followers, Muhammad found he had to flee Mecca for Medina. By 629, Muhammad had gained authority over both Mecca and Medina, both of which are considered holy cities within the Islamic faith. Note that Jerusalem, Karbala, and Najaf are all holy cities within Islam, but not as pivotal as Mecca and Medina throughout the entire faith.