Which of the following would be the best example of consumer surplus?

Select one:

a.

Jane pays $30 a month for phone service even though she was willing to pay up to$70.

b.

Sam refuses to pay $10 for a haircut because it is only worth $8 to him.

c.

Fred buys a car for $4,000 which is the maximum amount that he would be willing to pay for it.

d.When Sue purchases a candy bar for $.50, she uses a $20 bill to pay for it.