Answer B. Everyone in conquered lands was forced to convert to Islam.
After the death of Muhammad, Muslims created the concept of Caliphate to rule the lands conquered and implement domination of the territories. Islam spread through conquering other states and nations and implemented his culture, trade, and missionaries. Arab Muslim army imperial structures during the reign of the Rashidun(632 to 661).
Islam spreaded from the Arabian Peninsula to what is now Spain and portions of India.
