Final answer:
Johnny Longden's win after being rescued twice exemplifies situational irony, which is characterized by the contrast between expected outcomes and the actual result.
Step-by-step explanation:
The fact that Johnny Longden won the race after being rescued twice is an example of situational irony. Situational irony occurs when there is a discrepancy between what is expected to happen and what actually happens. In this case, the expectation might be that after needing to be rescued, a jockey would not be in a position to win a race. However, the surprising outcome defies these expectations as Longden not only competes but also secures a victory.