A very popular fast food restaurant specializing in sandwiches in the UK has recently raised the price of sandwiches by 0.2 euros, which refers to 2 euros from 1.8 euros. But just one month after the price increase, all waiters resigned in unison. Which of the following, if true, would best explain the above phenomenon? ['After the price rises, fast food restaurants can continue to give customers drinks, and the waiters are troublesome.', 'The tip for the waiter is much smaller than before. Because the price is an integer, the customer may not have changed.', "Although the price of sandwiches has increased, there has not been a corresponding increase in the waiter's salary.", 'Due to rising prices, except for some patrons who often come to patronize, the business in the store is getting deserted.']