What Is a Major Function of the President's Chief of Staff

What is a major function of the president's chief of staff?

A) Review the budget and legislative proposals of all the federal departments and agencies
B) Prepare the annual Economic Report of the President and recommend adjustments in government spending and taxation
C) Advocate for a specific group of citizens and provide services for that sector of society
D) Oversee the White House Office and control access to the chief executive
E) Coordinate domestic,foreign,and military policies and advise the president