Answer:
A. Poverty among Mexican Americans who had lost their land
Step-by-step explanation:
One long-term effect of American actions in the lands the country claimed after the Mexican-American War is that there is "Poverty among Mexican Americans who had lost their land"
Following the end of the Mexican-American war in early 1848. Mexican Americans with land ownership lost their land to the federal government of the United States.
Therefore, they were left with no land as a means of generating income particularly for farming to make money.
Hence, the majority of these people plunged into hardship and eventually poverty.