Why is the Khmer Empire called a "seed of culture"

a. many southwest Asian traditions grew out of that culture

b. many new crops grew during that time period

c. southeast Asia's population grew that period

d. southeast Asian's trading grew dramatically during that period

I believe the answer is: A. many southwest Asian traditions grew out of that culture

In the past, Khmer empire control a large portion of South East Asian territories. Since at that time South East Asia control the trade routes in all South Asia, the cultures and traditions that introduced by Khmer Culture was spread almost to all South Asian region.

The correct answer is a) - many traditions grew out of it. It was a time of great wealth, which contributed greatly to the development of art and architecture.