What Was a Source of Conflict Between the Mexican Government

What was a source of conflict between the Mexican government and American settlers in Texas in the 1820s and 1830s?

A) Mexico had abolished slavery, but many American settlers were practicing slavery in Texas.
B) The number of Tejanos in Texas was increasing faster than the number of American settlers.
C) The settlers were abolitionists, but Mexico legalized slavery.
D) Mexico would not allow American settlers to become Mexican citizens.
E) Mexico forced American settlers to convert to Catholicism.