100 POINTS please answer a.s.a.p.

The emergence of Islam in the 600s CE coincided with the beginning of Axum's long, slow decline. Islam spread throughout Arabia and into Africa shortly thereafter, though Muslim armies never actually conquered Axum. Which of the following is a result of the inability of Muslim forces to conquer Axum?
A. Present-day Ethiopia is a Christian country.
B. Muslim merchants refused to trade with Axum.
C. An especially mystical form of Islam developed there.
D. The kingdom became isolated from the rest of the world.