Compare the vulnerability of the heads of executive departments versus those of regulatory agencies.
A. Both types of heads can be fired at the president's will
B. Neither heads can be fired by anyone except a congressional committee.
C. The heads of the former can be fired at the will of the president; while the heads of the latter can't be fired during their terms except for extreme misconduct.
D. In the former, heads cannot be fired during their terms of service, while in the latter, the president can fire the heads at will.