The correct answer is B) Obtain the California territory.
The United States began the Mexican-American War after fighting broke out between disputed area located near the Rio Grande. One of the reasons behind this fighting was president Polk's insistence on manifest destiny. This was the idea that it was America' god given right to control all of the land in the North American continent (including modern day California). This war was short and resulted in the US gaining California, Arizona, New Mexico, Utah, and parts of Colorado in the Treaty of Guadalupe Hidalgo. This transfer of land from Mexico to the US is known as the Mexican Cession.
