Question

in desert areas, the exposed rocks develop a brown or black coating which is called ______.
a desert varnish
b desert pavement
c loess
d desert coating

Explanation:

Desert varnish is the thin, dark brown or black coating that forms on exposed rock surfaces in arid environments. Desert pavement refers to a surface of tightly packed rock fragments, loess is wind-blown silt deposits, and "desert coating" is not a standard geological term for this feature.

Answer:

a. Desert varnish