Photographer Nobuhiro

Test analysis: The material describes the economic phenomenon of agricultural development in Jiangnan area. The main reason for this phenomenon is that since the Wei, Jin, Southern and Northern Dynasties, northerners moved south, bringing advanced agricultural technology to develop Jiangnan area, and the economic center began to move south. So choose D.

Comments: The reasons for the shift of the economic center of gravity to the south are:

① There are more wars in the north and relative peace and stability in the south;

(2) A large number of farmers in the north moved to the south, bringing advanced production technology and supplementing the labor force in the south of the Yangtze River;

(3) Jiangnan rulers pay more attention to economic development in order to develop their strength;

(4) The working people in the north and south make joint efforts to develop Jiangnan;

⑤ The production conditions and natural environment in the south are superior.