Answer: a. increase the equilibrium price but the change the equilibrium quantity in either direction.
Step-by-step explanation:
When there is an increase in demand, it will cause the demand curve to shift to the right. This leads to it intersecting with the supply curve at a higher point where prices will be higher as shown by the graph.
As a result, the equilibrium quantity will also rise which means that supply will increase to cater for the new demand but will do so at a higher price to cater for scarcity.