Final answer:
The correct answer is (a. Santa Anna launches a revolution against President Bustamante), as Santa Anna's rise to power and overturning of the Mexican Constitution of 1824 led to the eventual Texas revolt and formation of the Republic of Texas.
Step-by-step explanation:
The completion of the graphic organizer concerning events related to the Texas Revolution and the formation of the Republic of Texas is option (a. Santa Anna launches a revolution against President Bustamante). This event is critical because General Antonio López de Santa Anna played a central role in the political and military conflicts of the period. Santa Anna gained popularity after defending Mexico from a Spanish invasion and then led a coup that replaced the Mexican president, subsequently becoming president himself in 1833. His conservative rule, particularly the replacement of the Mexican Constitution of 1824 with the Siete Leyes, concentrated power and dissolved Congress, which ultimately provoked the Texas settlers to revolt and defend the Constitution of 1824. Santa Anna's actions propelled the Texans towards their declaration of independence and the establishment of the Lone Star Republic.