Read the sentence below, and answer the question that follows. the old combine on the farm had not been operated in almost a decade, but after a few hours of work, it was operating flawlessly in the field. how many prepositional phrases are in the above sentence?
a. three
b. four
c. five
d. six

I believe that there are three prepositional phrases but if you would like to do it yourself instead of taking my word for it. a prepositional phrase is a modifying phrase consisting of a preposition and its object.
And a preposition is a word governing, and usually preceding, a noun or pronoun and expressing a relation to another word or element in the clause, as in “the man on the platform,” “she arrived after dinner,” “what did you do it for ?”