20. Employees should call a supervisor when a customer: a. makes several purchases with little regard for size, quality, or cost. b. charges expensive items on a newly valid credit card. c. cannot provide a photo ID when asked and rushes the employee. d. all of the above. 21. A valid "MasterCard" should have a signature panel with ... a. the multicolored word "MasterCard" at a 45 angle and the last 4 digits of the account number printed in reverse italics. b. nothing on it but the white space for the signature. c. a multicolored "MC" printed at a 90 angle and the last 4 digits of the account number printed in reverse italics. d. "MasterCard" printed many times but no digits