What Is the Meaning of the Phrase "The Closing of the Gates

What is the meaning of the phrase "the Closing of the Gates" to the Muslim ulama (religious scholars) ?

A) The ulama sought to close Islam to Christians and Jews.
B) The ulama convinced the majority of Muslims that God's laws had been made complete, so there was to be no further questioning.
C) The ulama generally rewrote religious laws to conform to their beliefs about God's will for his people.
D) The ulama brought the examples set by Muhammad to the center of Muslim religious belief.
E) The ulama seized power from the vizier, or prime minister.