Ethnic chinese living in south east asian countries have played an important role in

expanding sea trade.

Explanation:

The southeastern Asia is a subregion consisting of the geographically south china, east of the Indian subcontinent and the northwest of the Australian and has an area of  4,545,792 km square with a population of 655,298,044  and is 10.5% of the Asia and 3% of the Asian landmass. and forms the member of the ASEAN a regional organization that establishes the economic, the political, military, the educational and the cultural integration. Especially of the Vietnam in the northern parts and was under the dominance of the chines and this became a trading hub for the west and northwest and the silk route also has flourished due to there existence.

Ibelieve the answer is c

Answerhave flowing water either episodically or during only a portion of the year;