Which of the Following Is True About Administrative Agencies

Which of the following is true about administrative agencies?

A) They rarely have the power to both issue regulations and investigate when such regulations have been violated.
B) They may make regulations that are advisory in nature, but cannot make regulations that have the force of law.
C) They are, in theory, part of the executive branch of government, but they may also perform legislative and judicial functions.
D) They never adjudicate disputes involving the statutes they are charged with enforcing.