Which of the Following Is Correct with Regard to a Contract

Which of the following is correct with regard to a contract entered into with a third person by an agent of an undisclosed principal?

A) The agent has no liability to the third person if the agent has acted within the scope of her authority.
B) The agent is personally liable upon the contract.
C) Under the Second Restatement, once the third person learns of the existence and identity of the principal, that third person may hold both the principal and the agent to the performance of the contract.
D) Under the Third Restatement, if the third party obtains a judgment against the principal, the agent is discharged from liability to that third party.