During the course of their conquest, the Ottoman Empire contained many non-Muslim lands. Non-Muslims were granted religious freedom, but with large taxes added, which Muslims did not have. One such tax, which was the most difficult form of taxation ever, is the seizure of one son from every non Muslim family and their recruitment to Janissaries. Churches and temples built by non-Muslims had to be below the physical level of the mosque, often partially buried in the ground. The life of non-Muslims burdened with every tax was difficult, so they were indirectly forced to become Muslims.
The answer is: A.
