4. The function of the eukaryotic DNA replication factor PCNA (proliferating cell nuclear antigen) is similar to that of the B-subunit of bacterial DNA polymerase III in that it: (A) forms a circular sliding clamp to increase the processivity of replication. (B) increases the speed but not the processivity of the replication complex. (C) has a 3' 5' proofreading activity. (D) facilitates replication of telomeres. (E) participates in DNA repair.