In General, How Did Islam Spread in Southeast Asia

In general, how did Islam spread in southeast Asia?

A) Port cities were points of dissemination to other links in trading networks.
B) Most of southeast Asia was converted to Islam after the military victories of Qutb-ud-din Aibak.
C) Islam was carried to southeast Asia from China.
D) Trade to southeast Asia from Africa and Persia established Islamic centers on the mainland from which conversion took place.