Which of the Following Was Not One of the Background

Which of the following was not one of the background causes of the Mexican-American War?

A) Mexico had failed to pay $2 million in debts owed to U.S. citizens.
B) Northerners feared that the Mexican government would try to expand northward and extend the slave system.
C) Americans loathed Mexicans.
D) Texans balked at a U.S. attempt at annexation because they feared it would provoke a Mexican invasion and war on Texas soil.
E) Mexicans feared the United States might attempt to seize other provinces from Mexico.