What Led to a Fusion of Religious and Cultural Influences

What led to a fusion of religious and cultural influences in Southeast Asia?

A) Shinto monks sent missionaries to interact with Hindus and Buddhists in the area.
B) The region was repeatedly conquered by forces from India,China,and Korea.
C) The Khmer kingdom invited religious scholars from the Byzantine court and Japan to debate philosophy with Vedic leaders.
D) The Malay Peninsula was home to many entrepôts for a variety of merchants shuttling between India and China.