When gas station manager Roger Randolph realized it was costing him money each time someone filled up with $ 4 agallon gas, he hung a sign on his pumps: 'No more credit cards.' He may be the first in West Virginia to ban plastic, but gas station operators nationwide are reporting similar woes as higher prices translate into higher credit card fees the managers must pay, squeezing profits at the pump.'The more they buy, the more we lose, ' said Randolph, who manages Mr. Ed's Chevron in St. Albans.'Gas prices go up, and our profits go down.' His complaints target the so-called interchange fee—a percentage of the sale price paid to credit card companies on every transaction. The percentage is usually fixed at just under 2 percent but the dollar amount of the fee rises with the price of the goods or services. As gas tops $ 4 a gallon, that pushes fees toward 10 cents a gallon. Now stations, which typically mark up gasoline by 11 to 12 cents a gallon, are seeing profits shrink or even reverse. In a good month, Randolph's small operation would yield a $ 60 profit on gasoline sales. But that's been buried as soaring prices forced the station to pay about $500 a month in interchange fees.'At these prices, people aren't making any money, ' said Jeff Lenard, spokesman for the National Association of Convenience Stores.'It's brutal.' Lenard's group reports convenience stores paid roughly $ 7. 6 billion in credit card fees last year, while making $ 3. 4 billion in profits.
The credit card companies say fees are just part of the cost of doing business. MasterCard has capped interchange fees for gas purchases of $ 50 or more, said company spokeswoman Sharon Gamsin. Accepting MasterCard also gives gas stations 'increased sales, greater security and convenience, lower labor costs, and speed for their customers at the pump, ' Gamsin said in an e-mail to the Associated Press. Visa argues that the fees are offset 'by the tangible benefits to stations and their customers, such as the ability to pay at the pump, ' the company said in a statement to the AP.
Which of the following sentences can best describe the main idea of this passage?
A．The gas station operator begin to say 'no' to credit cards.
B．It is not convenient for both the customer and gas station manager to use credit cards.
C．Why do customers prefer to use credit cards?
D．How can small shops avoid customers using credit cards in the future?