I believe if I remember correctly, he/she is watching soldiers cross a waterway or bridge.
Tybalt sent Romeo a Challenge, and Its significant, because Romeo does not want to challenge Tybalt because they are ano cousins due to Romeo, and Juliets wedding. It's also important, because it leads to mercucio answering the challenge and ultimatley to Mercucio's death.
Answer:
The 3rd sentence is the sentence fragment.
