You Are Walking in the Mountains of Southern California and Discovery

You are walking in the mountains of southern California and discovery a small stream.One of the things you notice is that,although the surrounding habitat you recently ventured through was rather dry,this habitat is moist and many trees and plants are thriving along the stream where water is plentiful.How would you describe this part of the landscape?

A) These trees and plants are part of an arboreal forest.
B) These trees and plants are part of a riparian zone.
C) These trees and plants are no different from other species adapted to the surrounding arid environment.
D) None of the above.