Which of the following topics is an example of an impromptu or unplanned speech?

the best local hiking trails
a toast for a newly married couple
strange foods that people should try
why cell phones should be banned in restaurants

I feel that there should be more context for the question, since all of them can be topics for impromptu speech, simply if one has to hold a speech on them without preparation.

However, perhaps the most typical is the toast for a newly married couple - people rarely prepare toasts, although sometimes they do.

Creon believed a good leader should do whatever is best for his people and personal relationships should not affect one's decisions.