In the Formation of Biofilms, Such as Those Forming on Unbrushed

In the formation of biofilms, such as those forming on unbrushed teeth, cell signalling serves which function?

A) formation of mating complexes
B) secretion of apoptotic signals
C) aggregation of bacteria that can cause cavities
D) secretion of substances that inhibit foreign bacteria
E) digestion of unwanted parasite populations