Answer:
A. began the Mexican-American war
Step-by-step explanation:
The mexican-american war was a war fought between Mexico and the United States of America after the Mexican government failed to recognize the Velasco TReaty where they granted Texas independence and consequented annexation to the Union in 1845, it lasted 2 years and ended with the american army entering the capitol and a ratification if TExas independence and also granted more territory to the American Union, and recognized Rio Grande as the north border with the Union.