Guardian Security Inc. and Hedge Fund Corporation enter into an oral contract under which Guardian agrees to provide services for Hedge's offices for as long as needed. This contract may be enforceable by

A) Guardian only.
B) Hedge only.
C) any interested third party, such as one of the firms' employees.
D) either Guardian or Hedge.

This contract, despite being oral and for an indefinite period, can be enforceable by either party involved in the agreement (Guardian Security Inc. or Hedge Fund Corporation) if they can prove the existence and terms of the contract through their actions, invoices, payments, or any other form of evidence. Contracts do not necessarily need to be in writing to be enforceable, especially for services that can be terminated at will by either party.