Which of the Following Describes the Reason the Ottoman Sultan

Which of the following describes the reason the Ottoman sultan created the janissaries?

A) The janissaries maintained steadfast loyalty to the sultan,while limiting the autonomy of provincial rulers.
B) The janissaries were a group of Sufis whose task was to spread mystical insights throughout the region,connecting the Sultan to Allah.
C) The janissaries were used as conscript labor in Ottoman building projects,such as the Topkapi Palace.
D) The janissaries,conscripted from Muslim villages,were meant to maintain the religious purity of the bureaucracy.