Answer: C) When Alex came home, his parents were waiting up for him.
Explanation: a misplaced modifier is a word, phrase, or clause that is improperly separated from the word it modifies or describes. Because of the separation, sentences with this error often sound awkward, ridiculous, or confusing. In the sentence A, it isn't clear who was driving (the bears or the speaker), in sentence B, it isn't clear who was snoring (the alarm or the speaker), in sentence D it is unclear what was eight feet long (the surfboard or the store), so the sentence that uses a modifier correctly, is the corresponding to option C.
