The security officer at a large department store stopped a customer, Lisa, at the store exit, and asked to see her receipt for the goods in her possession, Lisa has four CDs in her possession, but her store receipt only lists three, Lisa says that the shop assistant said she could have the fourth CD for free because she is a loyal customer, and also because he likes her. The shop assistant confirms this is an accurate description of his conversation with Lisa, but the store has a strict policy prohibiting discounts without a manager's approval( which was not obtained here). Which of the following statements most accurately describes the situation, Explain your answer fully.

(a) Lisa has a binding contract for all four CDs

(b) Lisa has a binding contract, but only for three of the CDs

(c) There was no contract created because the shop assistant acted outside his authority