A) It forced the President to get Congressional support before hiring and firing government officials.
Explanation:
Andrew Johnson was not a president that was a supporter of Reconstruction efforts as he was from the South. Congress on the other hand, was controlled by stanch Reconstructionists and so they passed this Act to ensure that their people in his government such as Edwin Stanton who was the Secretary of War were protected from Johnson.
The Act required that Johnson could not fire certain government officials unless the Senate supported it.