The answer to this is 5. It might seem like a lot, especially since the sentence does not seem to be very long — a prepositional phrase, a phrase that will be modifying the preposition and its object. The object of the preposition is usually the word that is after the preposition. For example, in the sentence, the word During is the preposition, and the object is the month of May.
The more that you look at the sentence, the more that you will recognize the different prepositions. It will help if you have memorized the different prepositions that are available such as at, in, from, with, by, and about, just to name a few. The more that you know what the prepositions are. The easier it will be for you.