How can you transform the sentence "The girl won the prize" into a relative clause referencing "my sister"?

The correct transformation is achieved by focusing on the structure and clarity of the sentence. When you say "The girl who won the prize is my sister," you effectively create a relative clause that provides additional information about "the girl." The phrase "who won the prize" specifies which girl you are referring to, making it clear that the girl who has this defining characteristic is, in fact, your sister.

This construction adheres to the conventional format for using relative clauses, where the relative pronoun "who" is used to introduce extra information about a noun (in this case, "the girl"). This method maintains clarity and coherence, ensuring that the reader can easily understand the relationship between the girl and being your sister.

Other options may include elements that disrupt the natural flow or clarity of the information being conveyed, making them less effective at transforming the original sentence.