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

Refer to Figure $8-4.$ The equilibrium price before the tax is imposed is

a$.$

$$24,$ and the equilibrium quantity is $70.$

b$.$

$$10,$ and the equilibrium quantity is $70.$

c$.$

$$16,$ and the equilibrium quantity is $100.$

d$.$

$$8,$ and the equilibrium quantity is $100.$