Kevin has $20 to spend on summer clothes. He is looking at shirts, shorts, and flip-flops. Shirts are $10, shorts are $15, and flip-flops are $10. Which of the following statements best describes the opportunity costs and benefits of buying a shirt?

a.The opportunity cost is $10; the benefit is that he now has a shirt.
b.The opportunity cost is that he cannot afford the shorts; the benefit is that he now has a shirt.
c.The opportunity cost is $10; the benefit is that he saved $15.
d.The opportunity cost is that he cannot afford the shorts or the flip-flops; the benefit is that he saved $10.