Choose the word or phrase among A, B, C or D that best fits the blank space in the following passage

The Running of the Bulls is a (27)__________of the famous San Fermin festival - a practice that involves running in front of a small group of bulls (typically a dozen) that have been let loose on a course of a town’s streets. A first firework is set off at 8 a.m. to alert the runners that the corral gate is (28)__________ . A second firework signals that all six bulls have (29)__________ released. The third and fourth fireworks are signals that all of the herd has entered the bullring, marking the end of the event. Every year between 200 and 300 people (30)__________injured during the run (31)__________ most injuries are due to falls and are not serious. So you think you support it?

27. A. part  B. whole  C. section  D. piece
28. A. to close  B. closed  C. open  D. opening
29. A. be  B. been  C. being  D. to be
30. A. are  B. were  C. have been  D. had been
31. A because  B. so  C. although  D. but