The correct answer is C) waterways.
The other options of the question were A) camels. B) caravans. D) buffalo trains.
Waterways were the primary means that provided people and merchants of Korea, Japan, and Southeast Asia, with the ability to trade.
The orography in these countries allowed Japanese and Korean people to trade and transport goods, raw materials, and natural resources that represented the way to live and prosper. Merchants used the many rivers, lakes, and the sea to navigate and connect with other nations.