An on-going source of tension along the Texas-Mexico border was . a. livestock theft b. unstable government c. the spread of disease d. a lack of public schools

lifestck theft

Conflict with Mexico began when the United States annexed Texas as a state in 1845. Mexico claimed that the new border between Texas and Mexico was the Nueces River, while the United States contested the border was the Rio Grande.

Explanation:

pls mark brainliest:)

1775 is your answer hope this

it would be a. that is the only one i could think of