Even though there isn't an underlined word in this sentence, it is still possible to answer the question because of the options given.
Answer:
The underlined word is a preposition.
Step-by-step explanation:
The sentence "Will grandma stay in Florida through the winter?" does NOT have any interjections or conjunctions. An interjection has the purpose of conveying an emotion in an exclamatory way. For example: "Wow!", "Ouch!" etc. A conjunction is a word used to connect other words, phrases, or clauses inside a sentence. There are coordinating and subordinating conjunctions. For example: but, and, or, although, because, etc.
In the sentence, we do have prepositions. "In" indicates location, and "through" indicates, in this case, the duration of an action or state. It is important to note that "through" can also be an adverb or an adjective. As we can see, preposition is the only option that can be found in the sentence.