What might John have done regarding the story?

The choice indicating that Pippa could have told John the story reflects a possibility rather than certainty. This construction allows for the suggestion that Pippa had the opportunity or means to share the story with John, but it does not confirm that she actually did. It emphasizes the hypothetical nature of the situation, which fits well within discussions involving uncertainties or alternative outcomes.

In contrast, the other options either confirm that something definitely happened (as in the first and third choices) or suggest an absolute absence of knowledge (as in the fourth choice). While those responses are specific, they do not maintain the same level of openness to possibility that is characteristic of the correct answer. Thus, the second option effectively captures the uncertainty surrounding what John might have done regarding the story, making it the most appropriate choice.