Mina decides to spend three hours working overtime rather than going to the park with her friends. She earns $20 per hour or overtime work. Her opportunity cost of working is...
a.the $60 she earns working
b. the $60 minus the enjoyment she would have received from going to the park
c. the enjoyment she would have received had she gone to the park
d. nothing, since she would have received less than $60 worth of enjoyment from going to the park
