B. The region was repeatedly conquered by forces from India, China, and Korea.
The fusion of religious and cultural influences in Southeast Asia was primarily due to the region's long history of trade and conquest by outside forces, including India, China, and Korea. These interactions led to the exchange of ideas, beliefs, and cultural practices, which in turn gave rise to new religions and cultural traditions. For example, Hinduism and Buddhism were introduced to Southeast Asia by Indian merchants and missionaries, while Islam was introduced to the region by Arab traders and scholars. Similarly, Chinese culture and philosophy had a significant impact on the region, especially in areas such as Vietnam and Cambodia. Overall, the fusion of religious and cultural influences in Southeast Asia was a complex and ongoing process that reflected the region's diverse history and its interactions with neighboring societies.