Why was the Twenty-Fifth Amendment to the Constitution adopted?

Why was the Twenty-Fifth Amendment to the Constitution adopted?
 
  a. to clear up ambiguities over the constitutional provisions surrounding presidential powers to conduct war
  b. to clear up ambiguities over the constitutional provisions surrounding the role of the vice president should the president die or become incapacitated
  c. to clear up ambiguities over the constitutional provisions surrounding the president's powers to negotiate treaties
  d. to clear up ambiguities over the constitutional provisions surrounding the separate election of the vice president

Question -2-

Which of the following statements provides the best characterization of the members of the White House staff?
 
  a. The White House staff is a loose collection of bureaucrats who are loyal to executive agencies.
  b. The White House staff is composed of individuals personally and politically close to the president chosen specifically to serve the president's needs.
  c. The White House staff is composed of policy specialists who have little personal loyalty to the president.
  d. The White House staff is the link between executive agencies in the bureaucracy and Congress.

Question -3-

What describes Franklin D. Roosevelt's actions when he ordered the nation's banks to close temporarily during the Great Depression?
 
  a. He was exercising his power of executive agreement.
  b. He was acting independently and was going beyond the constitutional powers of the presidency.
  c. He was working within the powers granted to him by the Constitution.
  d. He was following the powers granted by Congress on crisis management.