Which sentence does not contain any errors in comma usage?
A.Well I'm not positive that's healthy.
B.While you are waiting, for the doctor, you should consider reading a magazine.
C.Running before dawn Billy got a good workout.
D.In the desk drawer, there is a spare key to the house.
D. does not contain any errors in comma usage because there's a subordiante clause and the main clause which is telling me about where the ' spare key to the house' is.
