Farming in the United States changed in many ways in the late 1800's:
A. The amount of money in circulation increased. Incorrect. Many farmers kept their money or saved it, there was really no circulation happening.
B. Farmers used new equipment. Correct. This is where the use of horses came into play to help plow fields, along with other pieces of equipment that made it easier to farm.
C. Larger farms produced a single crop. Correct. It was less work if a farm just had one crop, so larger farms would usually just pick one that was in high demand.
D. World competition decreased. Incorrect. The world competition did not decrease because of farming. World competition did maybe decrease for the farmers, but not in general.