Answer:
The statement that best describes how the outcome of the Mexican-American War supported Polk's presidential promises is:
C. As a result of the Mexican-American War, more land became available to white settlers.
Step-by-step explanation:
Polk's presidential promises, including his campaign slogan "54°40' or Fight!" and his expansionist policies known as "Manifest Destiny," aimed to acquire more territory for the United States. The Mexican-American War resulted in the signing of the Treaty of Guadalupe Hidalgo in 1848, which ceded a significant amount of territory, including present-day California, Nevada, Utah, Arizona, New Mexico, and parts of Colorado and Wyoming, to the United States. This acquisition of land fulfilled Polk's goal of expanding American territory and providing more land for white settlers.