单项选择题

Questions 23 and 24 are based on the following news. At the end of the news item, you will be given 10 seconds to answer the questions.
How did the accident happen

A.The gun fell to the floor, discharging as it hit the ground.
B.The boy shot his classmates intentionally.
C.Another person used the gun to shot two boys and one girl.
D.Not mentione