Representative democracy .modern nations including the united states have too many people for a direct democracy.
The correct answer is option d, that Santa Anna was quickly defeated at the Alamo.
Antonio Lopez De Santa Anna was the Mexican President at the time when the Texas revolution broke out in Mexico. Texas earlier was a part of Mexico, where land was so cheap that many Americans migrated to Texas. This revolution began because Tejanos ( Mexicans who lived in Texas) wanted to break away from Mexico on the issue of Slavery. Mexican laws opposed Slavery before the arrival of American, despite, Americans brought in slaves in Mexico. Therefore, the Tejanos and the Texans came together to fight for their freedom. For the suppression of the revolt president Santa Anna send an army to the fort of Alamo in San Antonio in 1836, but the army got defeat at the hand of the revolutionaries. After their victory in the revolt, they (Texans) formed the Republic of Texas.
It nearly doubled the size of the United States & it made it clear to other countries that America would try to salve problems/differences peacefully.