What Led to a Large Mexican Immigration to the U

What led to a large Mexican immigration to the U.S. in the 1880s?

A) They were recruited to work in the U.S. after the Chinese Exclusion Act of 1882.
B) The U.S. won millions of square miles from Mexico in the Mexican-American War and offered Mexicans U.S. citizenship.
C) There was a drought in Mexico which destroyed farm land and led to mass famine.
D) They were recruited to rid the Southwest of Indians who were still living there.