Why was the construction of the Grand Canal necessary?
a. The canal connected the Tang capitals Chang'an and Loyang with the newly acquired regions in the North.
b. Chinese population was increasingly concentrated along the northern plains of the Yangtze River.
c. Peasants were moving from the countryside of southern China to the urban areas of the North.
d. Major river systems in China ran from north to south, and the canal was necessary to connect the coastal regions with the western frontier.
e. The Yangtze River valley was becoming the major food-producing region of China by the late Tang era.
Answer: E