How Can Epigenetic Changes Explain Why Identical Twins Develop Different

How can epigenetic changes explain why identical twins develop different physical characteristics later in life?

A) Epigenetic changes are mutations that change the primary structures of proteins.
B) Epigenetic changes are changes that occur to proteins after they have been synthesized in cells.
C) Epigenetic changes are modifications of DNA and histones that change which genes are expressed.
D) Epigenetic changes are additions and deletions of DNA by the action of viruses that infect cells.