Choose the statement about surface mold and sapstain fungi that's true. a. they cause a burned or charred appearance on wood surfaces. b. they exist only in very dry conditions. c. they don't cause structural damage. d. they're the most common cause of wood decay.

The correct option is D
Both surface mold and sapstain fungi discolor the surface of woods that are used in building construction. Surface mold and sapstain fungi can not grow in dry condition, but when the wood is wet, they can grow very quickly and reproduce. This can be controlled by eliminating the surface of wetness. 

Honestly i have no i guess the creators didnt think of that