A) polymerize about 1000 nucleotides per second during DNA replication in vivo. B) are incapable of 3′-to-5′ exonuclease activity. C) are capable of 3′-to-5′ DNA polymerase activity. D) have a single active site that is used for both polymerization and editing. E) are unable to initiate polymerization de novo (i.e. in the absence of a primer).