The Main Problem That Stalled the Admission of Texas into the United

The main problem that stalled the admission of Texas into the United States was

A) the lack of enough people in Texas.
B) Texas's overly large debt, which would have to be assumed by the federal government.
C) that Texas would be a proslavery state.
D) that foreign nations had refused to recognize an independent Texas.
E) that Texas was still under the control of Mexico.