W: Are there any long rivers in Africa? M: Yes, for example, the River Nile is the longest fiver in the world. W: Is it Egypt? I hear that it used to flood large areas. What about it today? M: In order to control the flood and make electricity, people built the Aswan High Dam on the river. W: Then it is another interesting place, isn't it?, Question: Why did Egyptians build Aswan High Dam? (A) In order to sail upstream. (B) In order to control the flood. (C) In order to attract visitors.
(B) In order to control the flood.