Final answer:
The sentence that contains a prepositional phrase functioning as an adverb is D. 'Let's put the science book into your backpack so you can use it to study.' The phrase 'into your backpack' acts adverbially by modifying the verb 'put'.
Step-by-step explanation:
To identify which sentence contains a prepositional phrase that functions as an adverb, we need to locate phrases that provide information about how, when, where, or why something happened. An adverbial prepositional phrase will modify a verb, an adjective, or another adverb in the sentence.
Looking at the provided options:
- A. Surprised by Sam's sudden appearance in the doorway, Tina accidentally dropped the cake.
- B. The cheesy casserole on the counter took a long time to bake, but it smells delicious.
- C. If she had walked into the room five minutes earlier, the surprise would have been ruined.
- D. Let's put the science book into your backpack so you can use it to study.
The correct answer is D: "Let's put the science book into your backpack so you can use it to study." The prepositional phrase "into your backpack" tells us where to put the science book, which is functioning as an adverb modifying the verb 'put'.