Through this process, a group of people become naturalized citizens.
a. expatriation
c. exceptional naturalization
b. denaturalization
d. collective naturalization

It is through a process of "d. collective naturalization" that a group of people become naturalized citizens, since this is done to save time as opposed to naturalizing each citizen individually. 

The  most important advantage  of  northeast china  that  mainly contributed toward its being  the  industrialand  technological center  of the  country  in the  1970s  and  1980s  is:   its  juxtaposition with china's  most important industrial  neighbors.