单项选择题

Questions 4 to 7 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the question
Now, listen to the conversation.

What is the most possible reason for the English Channel to emerge

A.Because of a flood millions of years ago.
B.Because of an earthquake millions of years ago.
C.Because of a flood thousands of years ago.
D.Because of a volcano eruption millions of years ago.