Evaluate the advantages of perfectly competitive and monopolistic markets in the long run.

First, the key terms in the question should be defined; perfect competition, monopoly, and long run. This should be done in the first paragraph, to pick up to easy band 1 marks.

One could structure this answer in 2 ways; a running comparison/contrast between the two markets, with each paragraph constituting a point, or an entire section devoted to perfect competition then another to monopoly. The IB has explicitly stated it prefers the running commentary, and thus this is often the route that higher-scoring students use.

For example, one could answer with the fact that monopolies of economies of scale and a lower marginal cost - thus they can produce at lower prices. However, this does not mean that they will sell at low prices (as opposed to perfectly competitive firms which can, and must, to survive), and this opens up an argument on the advantages to the consumer, not only to the business.

Remember to add graphs whenever appropriate; the obvious two would be the long run curves for perfectly competitive and monopolistic markets.

The conclusion should not add any new information, merely reaffirm the key points you have made (and if you have time, structure them by importance).