The best answer is A: they were able to increase their productivity due to the popularity of tractors. In the 1940s, American farmers were impacted by the introduction of new technology, such as tractors, which allowed them to increase their productivity by making farming tasks faster and easier. This increased productivity led to an increase in the supply of agricultural goods, helping to feed the growing population and support the war effort. Farmers were not negatively impacted by new technology in the 1940s, as the choices C and D suggest.