The correct answer is C) proximity to China encouraged the spread of Buddhism and other practices South into Indochina.
The statement that describes how geography influenced the cultural development of Southeast Asia is proximity to China encouraged the spread of Buddhism and other practices South into Indochina.
The geograpih proximity of China to Southeast Asia helped the merchants to impulse trade practiced and allowed monks to travel by sea to this region to spread Buddhist ideas in Southeast Asia. With these trips, monks could interact with the natives of the region and influenced them with the Buddhist precepts.