A customer accuses you of giving them the wrong amount of change after paying for their groceries. In order to effectively deal with the complaint, you should:

a. express appreciation to the customer for letting you know and ask that they give you a few minutes to explore and rectify the inaccuracy.
b. challenge them, as you know you are right and have given the appropriate amount of change.
c. roll your eyes, sigh and ignore the customer as you call for your manager.
d. laugh at the customer for getting angry over a $1.50 error.