Answer the following question given this paragraph: 

A biofilm is a thin layer of bacteria that sticks to a surface. Cells in a biofilm are all alike, but they may play different roles, such as taking in nutrients or making the “glue” that sticks the biofilm to the surface. The sticky plaque that forms on teeth is a biofilm of bacterial cells.


Q: What is a thin layer of bacteria that sticks to a surface?


A:
a biolfilm