What did president james k. polk use as grounds for declaring war against Mexico?

a. annexation of Texas

b. declaration of the border

c. Mexican soldiers' attack on Zachary Taylor's forces

d. nonpayment of debts

One of the major things that President Polk used as grounds for declaring war against Mexico was " c. Mexican soldiers' attack on Zachary Taylor's forces," since this inspired the most patriotic fervor. Although the validity of these claims was highly questionable.