I believe in this case the correct answer that would complete the sentence is that:
In 1935, President Roosevelt began to “enact major new social welfare programs”.
Social welfare programs are programs by the government which are designed to help the citizens from economic hardships and other insecurities of life. Actually, it was President Roosevelt who in 1935 proposed to the Congress federal social relief programs and a retirement programs sponsored by the federal government. The major achievement was the passage of the 37 pages Social Security Act which successfully became a law on August 14, 1935 and became effective in 1939.