How can the group carry out their studiesA．By usin

单项选择题

Questions 11--13 are based on the following passage. You now have 15 seconds to read Questions 11--13.

How can the group carry out their studies

A．By using satellite images, maps, etc.
B．By studying specific farming methods.
C．By studying the variation of human population.
D．By analyzing the quality of crops.