which of the following statements currently BEST explains the problem with U.S. illegal immigration?

A. Illegal immigrants will work for lower wages so their skills are needed.
B. Mexico accounts for the most illegal migrants because of it's proximity to the U.S.
C. Most of the undocumented workers are couples with children living in poverty
D. Undocumented U.S. immigrants are having more children who are citizens of the U.S.