Answer:
D. over the hills, through the woods, to Grandma's house
Explanation:
A phrase consists of at least two words which together form a particular meaning. There are various types of phrases: noun, adjective, verb, prepositional, etc. In the sentence above, there are three prepositional phrases which consist of a preposition and a noun: over + the hills, through + the woods, to + Grandma's house.
A is not a phrase because it's a single word.
B is an incomplete, subordinate clause.
C are not all phrases in the sentence - through the woods is missing.