From 800–1200, the khmer and mon peoples moved into the northern regions of
a. cambodia.
b. thailand.
c. vietnam.
d. myanmar

The question is the following: from 800–1200, the Khmer and Mon peoples moved into the northern regions of... To answer this, it is important to know that around 800 is when the Khmer empire was created - and the Khmer empire was the state out which modern Cambodia is the succesor of. The answer is a) Cambodia

Assuming this is a question on a test just name a restaurant by your house and the state you live in, its not too difficult : )

Answer meranesia;