Which U.S. territory was acquired through the Treaty of Guadalupe Hidalgo?

The U.S. territory acquired through the Treaty of Guadalupe Hidalgo is primarily California and parts of the Southwest, which is reflected in the correct answer choice. This treaty was signed in 1848, concluding the Mexican-American War and marking a significant territorial expansion for the United States. As a result of this agreement, the U.S. acquired an extensive amount of land, including present-day California, Arizona, New Mexico, Nevada, Utah, and parts of Colorado and Wyoming.

In contrast, Texas was annexed by the United States in 1845 before the treaty, and Alaska was purchased from Russia in 1867, which are reasons those choices do not apply to this question. Similarly, Hawaii was annexed later in 1898 and was not involved in any agreements related to the Treaty of Guadalupe Hidalgo. Thus, the treaty's clear association with the acquisition of California and the Southwest makes that answer the most accurate.