The correct answer is C.
The Great Depression generated refusal to classic economic theories, which supported no goverment intervention in the economy and claimed that the free interactions of economic agents in the markets led to the most efficient market outcomes.
This refusal grew specially after President Roosevelt implemented the New Deal in the US. This was a package of measures that aimed to restore the economic conditions by using an intense schedule of goverment interventions in the economy, that sucessfully increased public spending to create job positions and to boost GDP levels.