Which of these is an example of economies of scale? a. a shoe store finds it can increase profits by hiring high school students who are willing to work for minimum wage. b. a ranch increases its profits by expanding from 400 to 800 cattle without buying or renting additional land. c. a restaurant charges customers $1 a glass for water that was once provided for free. d. an internet access company charges customers different rates for using the internet at different times of day?