单项选择题


Questions 21 to 23 are based on the following news. At the end of the news item, you will be given 15 seconds to answer the questions.
Now listen to the news.

What was the cause of the explosion

A.Children playing with fire.
B.The setting off of fireworks in a house with explosives.
C.Sparks from a fireworks display falling on the warehouse.
D.The firing of a gun.