The Epsilon (ε)Subunit of DNA Polymerase III of E

The epsilon (ε) subunit of DNA polymerase III of E.coli has exonuclease activity.How does it function in the proofreading process?

A) The epsilon subunit can remove a mismatched nucleotide.
B) The epsilon subunit excises a segment of DNA around the mismatched base.
C) The epsilon subunit can recognize which strand is the template or parent strand,and which is the new strand of DNA.
D) It adds nucleotide triphosphates to the 3′ end of the growing DNA strand.