In the Mexican-American War, Why Was the United States Victorious

In the Mexican-American War, why was the United States victorious in virtually all its encounters with Mexican forces?

A) Santa Anna refused to risk his troops in a direct fight.
B) The United States possessed superior artillery and supplies.
C) American generals employed the new military doctrine of "the static army" and remained in one location, forcing the Mexicans to travel hundreds of miles to encounter them.
D) the American army outnumbered the Mexicans at virtually every battle.
E) President Polk reassigned half of Winfield Scott's forces to General Taylor.