Mark wants to buy a new computer and apply for a new credit card to pay for it. He checked his credit report and credit score. His credit score is 620. It is fair, but Mark wants a lower interest rate and a higher limit. So he wants to improve his score. Which should Mark do to increase his credit score? A)Pay off his personal loan for his entertainment system. B)Skip a car payment. C)Apply for as many credit cards as he can. D)Make lower monthly payments on his current credit card bill.