Which is new technology of the 1800s had the greatest impact on farmers in the great plains?

the automatic harvester hope it helped

Well from the given answers it would be most likely D. Although this answer is not completely true and I am not completely sure why it is stated that way. The Truman Doctrine states in simple terms that any country trying to spread communism into another country would be subject to USA intervention. These answers sound biased and there’s really not a correct one but D is the “most” correct and I mean that in a very sarcastic way.