Figure $8-3$

The vertical distance between points A and B represents a tax in the market.

A graph of price, P$,$ versus quantity, Q$,$ shows a supply curve, S$,$ rising linearly from point $(0,4)$ to $(50,44),$ and a demand curve, descending linearly from point $(0,44)$ to $(52,2).$ The curves intersect at $(25,24).$ Point A lies on the demand curve at point $(15,32).$ Point B lies on the supply curve at point $(15,16).$

Refer to Figure $8-3.$ Suppose a $20$ th unit of the good were sold by a seller to a buyer. Which of the following statements is correct?

a$.$ For the $20$ th unit, the difference between the buyer's value and the seller's cost is equal to the tax per unit.

b$.$ It makes sense for the buyer to buy and for the seller to sell the $20$ th unit, with or without the tax in place.

c$.$ For the $20$ th unit, the difference between the buyer's value and the seller's cost is greater than the tax per unit.

d$.$ For the $20$ th unit, the difference between the buyer's value and the seller's cost is less than the tax per unit.