How did Roosevelt change the role of the U.S. president during the New Deal?

How did Roosevelt change the role of the U.S. president during the New Deal? (4 points)

a. He damaged long-term relations between the president and Congress.
b. He added to the president’s prestige in foreign relations.
c. He strengthened the authority of the office to make policy.
d. He weakened the powers of the office in domestic affairs.