Question

after the signing of the treaty of guadalupe that ended the u.s.-mexican war, mexican citizens living within the territory ceded to the u.s. were

given the opportunity to become u.s. citizens.
were forced to move south to mexican territory.

had their land taken by the u.s. government.

were sentenced to prison for treason.

Explanation:

The Treaty of Guadalupe Hidalgo (which ended the U.S.-Mexican War) provided that Mexican citizens in the ceded territory could choose to become U.S. citizens (with the option to remain Mexican citizens by relocating, but most stayed and were given the chance for U.S. citizenship). The other options are incorrect: they were not forced to move south, their land was not generally taken by the U.S. government en masse due to the treaty (though land disputes later arose), and they were not sentenced to prison for treason.

Answer:

A. given the opportunity to become U.S. citizens.