Which of the Following Explains Why the Federal Government Bureaucracy

Which of the following explains why the federal government bureaucracy exists? 

A) Bureaucrats work in different branches of the government irrespective of their area of expertise. 
B) Congress, over time, has delegated certain tasks to specialists. 
C) The power to act resides in the person rather than in the position. 
D) People are hired on the basis of their work experience instead of merit. 
E) Different operating procedures are followed depending on circumstances.