Which Statement Is a True Statement? Agency Agreements

Which statement is a true statement? Agency agreements

A) may only be terminated by notice given,or by the death,insanity,bankruptcy of either principal or agent.
B) are agreements of utmost good faith on the part of the agent.
C) if arising other than through operation of law or by necessity,must be in writing to be valid.
D) would not include,by definition,Powers of Attorney.