The correct answer is D. new territory that contributed to the formation of seven new states.
After the Mexican-American War, the US and Mexico agreed to the Treaty of Guadalupe Hidalgo. This treaty favored the United States heavily, as they won the Mexican-American War. The ultimate goal of this war was to gain land from Mexico, which they accomplished. The Mexican Cession resulted in the United States gaining several thousand square miles of territories. This would result in the creation of states like California, Arizona, New Mexico, Utah, Colorado, etc.
