Permanent Streams in Desert Regions Are Rare,and When They Do

Multiple Choice

Permanent streams in desert regions are rare,and when they do occur,________.

A) they originate in a glacier region
B) they have numerous tributaries to keep them supplied with water as they cross the desert
C) they originate outside of the desert region and have few tributaries in the desert
D) they get their water from wadis and arroyos