The correct answer is 4. Sink
Explanation:
In grammar, a preposition refers to a type of word that links nouns or pronouns with other words in a sentence and include words such as from, to, before, by, among, until, in, etc. On the other hand, the object of a preposition refers to the noun or pronoun that is placed after a preposition or the object the preposition is connected which completes ideas in a sentence. This means int eh case of the sentence "Please scrape the dishes and put them in the sink" the preposition is "in" and therefore the object of this preposition is "the sink" or "sink" because this is the object the preposition connects to the rest of the sentence.
