ulie spends all of her income on retail chain coffee and pizza. Coffee costs $4 per cup, and pizza costs $2 per slice. When Julie's income is $50 per week, she buys 5 cups of coffee and 15 slices of pizza. When her income rises to $80 per week, she buys 15 cups of coffee and 10 slices of pizza. Which of these statements is TRUE? A. Both retail chain coffee and pizza are normal goods. B. Retail chain coffee is a luxury good. C. Pizza is a luxury good. D. Both retail chain coffee and pizza are inferior goods