A very popular ice-cream shop recently raised the price of an ice-cream soda by $0. 20, from $1. 80 to $2. 00. Within a week of the price increase, all of the waiters-and waitresses had quit. Which of the following, if true, would most help to explain the resignations of the waiters and waitresses? ['The price increase allowed the shop to retain its popular generous portions of ice cream.', 'The waiters and waitresses received fewer tips than before because the increased price deprived customers of change that many had left as tips.', 'The increased price of ice-cream sodas did not affect the wage rate at which the waiters and waitresses were paid.', 'Regular customers continued to frequent the shop, despite the increase in the price of ice cream sodas.']