The answer is D
Reason: Because It’s D
I believe it is a metaphor because it compares the public and swine without the use of like or as.
I agree with your answers for 13 and 14. I think that the answer to 15 is A because the passage mentions this day's black fate and the woe that others will face in the future. If I remember correctly in this scene Romeo is talking about what repercussions Mercutio's death will have on the future.