Read the information below:

During the 1820s and 1830s, many people settled in Texas and California. The territories were part of Mexico. Some thought that the United States should annex those territories. The territories were soon independent of Mexico. They became part of the United States.

Which of the following supports this passage?

A) Mexico and the United States claimed different national boundaries until the 1840s.
B) Mexico did not have very tight control over its northern territories.
C) Texas and California needed U.S. military aid to gain independence from Mexico.
D) Texas and California were only sparsely populated before the 1820s.