The Law of April 6, 1830 signaled a major shift in:

A. The United States' diplomatic relations with Texas

B. The American policy of westward expansion

C. The land rights of Tejano farmers

D. Mexican treatment of American immigrants

The Law of April 6, 1830 signaled a major shift in "Mexican treatment of American immigrants".

Option: D

Explanation:

Law of April 6, 1830 was released to address fears that Mexican Texas, part of the border state of Coahuila Tejas was in danger of being occupied by the United States due to the extreme Mier Teran Report. U. S. citizens' immigration, some legal, others illegal, had quickly begun to intensify.

The law explicitly prohibited any further American colonists from wanting to settle in Mexican Territory. It also prohibited slavery in Texas. Contracts for settlements were put under federal instead of state control and colonies not having at least 150 settlers would be cancelled.