The function of the eukaryotic DNA replication factor PCNA (proliferating cell nuclear antigen) is similar to that of the $\beta$ subunit of bacterial DNA polymerase III in that it:

A) facilitates replication of telomeres.
B) forms a circular sliding clamp to increase the processivity of replication.
C) has a 3ʹ $\rightarrow$ 5ʹ proofreading activity.
D) increases the speed but not the processivity of the replication complex.
E) participates in DNA repair.