Which of the Following Is NOT a Key Issue at the Center

Which of the following is NOT a key issue at the center of the American immigration debate?

A) how to deal with the existing pool of undocumented people in the United States
B) the number of legal immigrants who should be allowed on an annual basis
C) whether to tighten the U.S.-Mexico border
D) drug trafficking (and the associated violence with drug trafficking) along the U.S.-Mexico border
E) whether to build a fortified border wall along the Canadian border with the United States