Agency relationships can be created by an understanding between an agent and a principal which may be:

A) Novation, Termination, Quantum Meruit, Specific Performance
B) Ratification, Duress, Misrepresentation, Warranty
C) Express or Implied, Formal or Informal, Gratuitous or Compensated
D) Accord and Satisfaction, Quasi-Contract, Injunction, Rescission