It was difficult for the united states to annex texas because
a. texas was an independent nation.
b. texas did not want to be annexed.
c. texas was already a us territory.
d. texas was governed by mexico.

The correct answer is - Texas was an independent nation.

The annexation of some territory is usually easiest when the population and officials in that territory want to join the country that wants to annex them, and of course if the country has a sufficient military power to manage to perform that, But Texas was not a Mexican province anymore, instead it was an independent country, and it had it pretty good both from political and economic point of view, so the Texans were not really passionate about joining the United States as they were not seeing the point and benefit for them from such an action.

d. direct

what are the options ?