The marginal cost of producing T-shirts at Harry's T-shirt Emporium is as follows: the first T-shirt costs $8; the second T-shirt costs $9.50; the third T-shirt costs $11; the fourth T-shirt costs $14.00. If the price of T-shirts equals $10, what is the producer surplus that Harry's T-shirt Emporium receives from selling T-shirts?

a. $0.50

b. $1.50

c. $2.50

d. $5.50