The correct options are
A Marxists blamed Capitalism for causing Great Depression.
D Franklin D. Roosevelt introduced the social security system in the USA.
Then US President Franklin D. Roosevelt, introduced a relief programme known as the “New Deal”, to combat the effects of the Great Depression. Economists like J M Keynes insisted on the role of the state or the government in such a crisis. Keynes argued that a state or government is responsible for keeping the economy healthy. So, if the economy falls due to a decline in demand, the state must invest money and generate more employment, which will help people earn more money and demand goods.