Answer:
d. price floor
Step-by-step explanation:
A price floor is a government mandated mininum price that is higher than the market equilibrium price.
This means that supply and demand do not meet because prices are not allowed to go any lower than the price floor.
The most famous example of a price floor is the minimum wage. A minimum wage is a price of labor that is higher than the market equilbrium. This produces a surplus of workers because supply (workers) is higher than the demand for them (which is determined by the firms).