Explain, in the context of market failures, what is meant by a positive externality. [1] Consider the market for fire extinguishers. Assuming fire extinguishers are currently sold at a constant price P, draw a graph labelling the demand curve and the marginal social benefit. Identify on the graph the market equilibrium level of output and the socially optimum level of output. [3] Outline the form of government intervention you would recommend in this scenario. [1]