The layout of this question is all AO1, it's an explanation, not an evaluation. Therefore you should only outline what the theory shows. For this question you need to explain both classical and operant conditioning. It is important to state that the explanation was developed by Mowrer, you do not need to remember dates though. Make it clear that classical conditioning forms a phobia, and operant conditioning maintains the phobia. You should give an example to explain classical conditioning, for example, somebody afraid of dogs. A neutral stimulus (such as a dog) is paired with a feared stimulus (being bitten) and it leads to a feared response. This causes the dog to become a conditioned stimulus that elicits a feared response (conditioned response). You would then go on to explain operant conditioning and negative reinforcement. This is when people feel rewarded for avoiding the feared stimulus and so they are more likely to repeat the behaviour. Lastly, you could include the theory of generalisation, where people can form fears of objects similar to their original feared stimuli. For example, Little Albert became scared of a fur coat when he was conditioned to be scared of a white rat.