With Respect to the Formation of Agency by Estoppel, Which

With respect to the formation of agency by estoppel, which of the following statements is true?

A) When a third party suspects that the agent he deals with has no authority, there is no obligation on him to question the agent's alleged authority.
B) The issue of apparent authority arises only if a person acts as an agent when he has express or implied authority.
C) If the principal tells an agent specifically not to sell something and the agent, in disobedience of those instructions, sells it anyway, the principal may be bound by the contract because of estoppel.
D) When a party terminates an express agency agreement with his agent and notifies third parties with whom that agent normally dealt, that party will be liable on a contract made for him by that "fired" agent.
E) When a party represents, by words or conduct, that someone is his agent, that party can later deny liability on a contract made for him by that agent on the basis that no express agency agreement existed.