What Did the Wilmot Proviso of 1846 Propose

What did the Wilmot Proviso of 1846 propose?

A) Slavery would be allowed to expand only into the area below the southern boundary of Missouri.
B) Any slaves taken in the area ceded by Mexico would be freed at age twenty-eight.
C) People living in the area ceded by Mexico could choose for themselves whether or not to permit slavery.
D) Slavery would be prohibited throughout the entire area ceded by Mexico.