I couldn't find C. D. living with his parents in 1900. But I found a Clarence Marsh,nephew, age 13 living with a James Marsh in Wellston, OH (Jackson County). There was a Ralph Marsh, another nephew, 6, both Clarence and Ralph born in Ohio. Could this be your Clarence?
Here is the rest of the household:
James,W. Marsh, 46
Roy Marsh, 24
Stella Marsh. 22
Walker J. Marsh, 15
Gertrude Marsh, 12
Ralph 6. Roy, Stella, Walker, and Gertrude were James' children.
What do you think?