Answer:
Correct answer is Texas annexation to the U.S.A.
Step-by-step explanation:
First option is not correct as Texas gained independence from Mexico in 1836.
Second option is correct as on March 1st resolution was passed and on December 29th Texas was admitted to US.
Third option is not correct as Texas never separated from United States.
Last option is not correct as Texas didn't gained independence from Spain. It was a part of Spain until 1821, and from that period until 1836 part of Mexico.