The Following Questions Refer to the Excerpt Below

The following questions refer to the excerpt below.
Commandancy of the Alamo
Bejar,Feby.24,1836
To the People of Texas & All Americans in the World
Fellow citizens & compatriots
I am besieged,by a thousand or more of the Mexicans under Santa Anna I have sustained a continual Bombardment & cannonade for 24 hours & have not lost a man The enemy has demanded a surrender at discretion,otherwise,the garrison are to be put to the sword,if the fort is taken I have answered the demand with a cannon shot,& our flag still waves proudly from the walls I shall never surrender or retreat.Then,I call on you in the name of Liberty,of patriotism & everything dear to the American character,to come to our aid,with all dispatch The enemy is receiving reinforcements daily & will no doubt increase to three or four thousand in four or five days.If this call is neglected,I am determined to sustain myself as long as possible & die like a soldier who never forgets what is due to his own honor & that of his country VICTORY OR DEATH.
William Barret Travis,
Lt.Col.comdt.
P.S.The Lord is on our side.When the enemy appeared in sight we had not three bushels of corn.We have since found in deserted houses 80 or 90 bushels and got into the walls 20 or 30 head of Beeves.Travis
-The conflict descried in this passage was part of which of the following contemporary trends?

A) Efforts of the United States federal government to control and relocate American Indian populations.
B) Efforts of American political leaders to expand government policies designed to unify the economy.
C) Efforts by American citizens to, through frontier settlement, extend the influence of the United States.
D) Efforts of other nations to, using military force, undermine American national sovereignty.