Final answer:
The three prepositional phrases in the line are 'Over the river,' 'though the woods,' and 'to grandfather's house,' corresponding to option A.
Step-by-step explanation:
In the line, "Over the river and through the woods to grandfather's house we go," the three prepositional phrases are as follows: 'Over the river', 'though the woods', and 'to grandfather's house'. These phrases indicate movement from one place to another, and each phrase starts with a preposition, which is followed by a noun or pronoun that is the object of the preposition. The correct answer to the question is A) Over the river, though the woods, to grandfather's house. Prepositional phrases often provide us with details about the direction, location, or time and can modify nouns or verbs within a sentence.