Turning cultivated land back into forests or pasture is a fundamental way to stem soil ______ and desertification in the long run.

A．It has little influence on the forum sponsored by the Crime and Justice network.
B．Neither supporters nor opponents of gun control cite the works of scholars.
C．The works of mainstream social scientists have great impact on it.
D．Many social science historians have so far failed to take part in it.

A．resolving a public dispute over gun control
B．describing the effects of earlier studies on gun control
C．analyzing the flaws in the previous theories about gun control
D．summarizing the recent development in the studies of gun control