The "white line" which shows up occasionally when finishing a composite restoration between the restoration and tooth structure is caused by what?
A . The inherent optical properties of composite which naturally create a halo effect around the margin
B . Overheating the composite during the finishing process
C . Polymerization shrinkage, which tears the composite at the margin with the tooth
D . Uncured resin that turns white in color during polishing
Answer: C