United States voters showed they wanted to annex Texas by

electing James K. Polk president.

Explanation:

The United States voters elected the pro-annexation Democrat, James Polk, against Henry Clay in the 1844 presidential election. Bills were passed by both arms of the congress to give the President-elect, Polk, options to get Texas annexed as soon as he took over office.

James Knox Polk went ahead to serve the people of the United States of America, as their 11th president from 1845 to 1849. Before he became president, he had served as Speaker of the House of Representatives and governor of Tennessee.

C. Because I'm a Texan and I know.