What probably happened in the given-below case?

The most likely scenario here is that Turner heard that there was going to be rain. You can make this inference by looking at what he grabs: an umbrella. The inference also makes sense because Turner mentions that the day is rather sunny at that moment. However, if he has heard a weather report that says there will be rain that day, there is a feasible reason to carry the umbrella.

The other inferences don’t make a lot of sense. We don’t get a lot of information about Turner’s personality, so we can’t infer that he likes to do silly things. There’s nothing mentioned about a possibility of the radio falling. As for trading the umbrella for a bus ride, there are usually bus cards or tokens, or a fee that one pays. No trading needing.