What was U. S. President Polk’s original reason for war with Mexico? What was the final reason?

https://millercenter.org/president/polk/foreign-affairs#:~:text=In%20late%20April%201846%2C%20Mexican,nations%20officially%20were%20at%20war.

Explanation:

i believe that the correct answer is a canadian hero.

explanation: he is celebrated as a national hero in canada for successfully thwarting a united states takeover of canada during the war of 1812.

the anwser is a) to prevent military conflict