Benvolio will be right, and Romeo will forget all about Rosaline.
Romeo and Benvolio will be revealed as Montagues, and a fight will break out.
Juliet will make a decision about whether she wants to marry Paris.
The question asks about your personal opinion when it says, "What do you think". However, there are some choices that make the most sense based on what you know because of any prior knowledge you have of the story and the prologue. We know that Romeo will not be with Rosaline in the end, so it would be logical to think that she is no longer a love interest of his when he sees Juliet at the party. Also, the prologue mentions that there will be new mutiny in regards to the ancient grudge, so we can expect more fighting. Last, we know that Juliet has to make a decision about marrying Paris at the party because of the conversation she had with her mother. Of course, we know what that decision will be, but still.
