An exotic stream is a. a river involved in a particular historic event b. a river who flows from a region with a large amount of precipitation to a desert c. a river who flows from a desert to a region with a large amount of precipitation d. a river found only in the tropics

B, a river that flows from a region with a large amount of precipitation to a desert

Explanation:

An exotic stream is a stream that has its source in well-watered lands and crosses a desert on its way to a sea. This type of stream is mostly found in places to dry to have produced such stream, so the flow originated in a place of a water source such as a lake or a sea. This stream begins in a humid climate and ends in an arid one. The discharge (volume) of an exotic stream decreases down slope because of evaporation and reduction in precipitation.

Some examples of exotic streams are the Nile and Colorado Rivers.