Answer:
It is C.
Step-by-step explanation:
After the US annexed Texas, it was really forever part of the US. (exception: Civil War).
A is wrong because the Texans lost the Battle of Alamo, it also occured in 1836, not 1845.
B is wrong, because it is not significant.
C is correct.
D is wrong, the Spanish left Texas nearly 2-3 decades ago.