Identify the true statement. choose one: a. the sahara desert has always been an arid region with few surface-water streams. b. oases are sourced by springs and are regions where groundwater intersects the land surface. c. there are no groundwater reserves beneath deserts like the sahara because there are no rocks present that would make suitable aquifers. d. in dry regions where surface water has disappeared, groundwater can no longer be found beneath the surface.