Answer:
Letter C is the correct answer.
Step-by-step explanation:
An adverbial clause of condition provides a situation under which an effect will happen under specific causes. Some of the most common words to indicate this clause of condition are if, whether, unless, among many others. In the sentence we can see how it starts with the word if, indicating the cause, and the effect is seen after the coma. Since past and present perfect are used ("Cassie's team had won" and "would have been thrilled), this is an example of third conditional, used to describe imaginary situations with results in the past.