From Reading the Periplus and Relating It to Archaeological Discoveries

From reading the Periplus and relating it to archaeological discoveries today,scholars have deduced that trade was very active on the southwestern coast of India because

A) Foreign ships were too big to travel through the shallow waters between India and Sri Lanka.
B) Since Buddhism rejected wealth, very little trade was carried out on the eastern coast of India.
C) Goods from the southwestern coast area had the most precious goods to trade.
D) Foreigners were able to pay in Roman and Greek coins.
E) Precious goods on the eastern coast must be paid for in Roman and Greek coins.