Figure $4-13.$

In the market for milk, the horizontal line, P$,$ represents a price ceiling of $$1\mathrm{.}00.$

The graph shows a demand and supply diagram, plotting price versus quantity for the market for milk. A demand curve is labeled D; it descends linearly from left to right. A supply curve is shown and is labeled S$.$ The supply curve ascends linearly from left to right. The demand and supply curve intersect at the point $(700,1\mathrm{.}50).$ Other points on the demand curve are $(600,2\mathrm{.}00),(800,1\mathrm{.}00)$ and $(900,0\mathrm{.}50).$ Other points on the supply curve are $(300,0\mathrm{.}50),(500,1\mathrm{.}00)$ and $(900,2\mathrm{.}00).$ A horizontal line is drawn on the diagram at the price $1\mathrm{.}00,$ which intersects the demand curve at quantity $500$ and the supply curve at the quantity $800.$

Refer to Figure $4-13.$ Which of the following is true?

a$.$ At the equilibrium price, the quantity demanded is $800$ gallons.

b$.$ The price ceiling will create a surplus of $300$ gallons.

c$.$ Buyers will wish to purchase $500$ gallons at the $$1$ price ceiling.

d$.$ Sellers will supply $500$ gallons to the market at the $$1$ price ceiling.