It Appears as If More Recent Channels in the Alluvial

Multiple Choice

It appears as if more recent channels in the alluvial fan complex shown below are lighter in color than the general surface of the fan.What geologic process could have caused this effect?

A) removal of desert-varnished clasts during formation of the channels, thus exposing less varnished and lighter colored material
B) the longer and bigger growth of plants on the areas between the recent channels, which from this far away cause the intrachannel areas to appear darker
C) transport of a large amount of dark-colored material out of the canyons during recent storms
D) the formation of inselbergs