The table below gives the costs and benefits of a firm operating under perfect competition: its activities create a certain amount of pollution. Assume that the costs of this pollution to society can be accurately measured.

(a) What is the profit-maximising level of output for this firm?

(b) What is the socially efficient level of output?

(c) Why might the marginal pollution costs increase in the way this example illustrates?

Output (units)	Price per unit (MSB)  (£)	Marginal (private) costs to the firm (MC) (£)	Marginal external (pollution) costs (MEC) (£)	Marginal social costs (MSC = MC + MEC) (£)
1	100	30	20	50
2	100	30	22	52
3	100	35	25	60
4	100	45	30	75
5	100	60	40	100
6	100	78	55	133
7	100	100	77	177
8	100	130	110	240