Congress passed the tenure of office act in 1867 to
a)change the approval process for appointees to require approval by two-thirds of the senate.
b)prohibit president johnson from firing government officials without senate approval.
c)extend greater rights to african americans.
d)limit the power of southern politicians.

B) prohibit President Johnson from firing government officials without Senate approval.

Explanation:

The Tenure of Office Act was passed by Congress on March 2, 1867. President Andrew Johnson endeavored to veto the law yet fizzled. The reason that Congress passed the Tenure of Office Act was to restrict the President's forces and counteract President Andrew Johnson expelling radical Republicans from office.  

The President in this manner disregarded the Tenure of Office Act and suspended Edwin Stanton, the Secretary of War and an unmistakable bureau part. This action prompted the Impeachment of Andrew Johnson.