Suppose it takes Dan 5 minutes to make a sandwich and 15 minutes to make a smoothie, and it takes Tracy 6 minutes to make a sandwich and 12 minutes to make a smoothie. What is the opportunity cost to Dan of making a sandwich?

Suppose it takes Dan 5 minutes to make a sandwich and 15 minutes to make a smoothie, and it takes Tracy 6 minutes to make a sandwich and 12 minutes to make a smoothie. What is the opportunity cost to Dan of making a sandwich?
A.1/3 of a smoothie
B.5 smoothies
C.15 smoothies
D.3 smoothies
正确答案：1/3 of a smoothie