If the Law Changes Such That the Actions Called for in an Agency

If the law changes such that the actions called for in an agency arrangement become illegal after the agency has been carried on legally for some period of time,what is the consequence?

A) The agency is terminated retroactively and the parties are left where they are.
B) The agency is terminated retroactively and the parties must each return any consideration received from the other.
C) The agency is terminated effective upon the change in law taking effect.
D) The agency is not terminated,but the principal and agent will each become liable for his or her own illegal actions.
E) The agency is not terminated,but the principal and agent will each become liable for the illegal actions of the other.