What is a biofilm? A layer of sugars that persist even after bacteria have been killed by antibiotics A group of bacteria that accumulate in layers and secrete an protective extracellular material Free-floating bacteria that move through the blood to other sites A bacterial cell that secretes an extensive network of fibers around its cell wall

Answer: A group of bacteria that accumulate in layers and secrete an protective extracellular material

Explanation:

Biofilm comprises any spectrum of microorganisms, including pathogens in which cells stick to each other and to a surface, so they become adherent cells. These cells become embedded within an extracellular matrix that is composed of extracellular polymeric substances (polysaccharides, lipids, proteins and DNA) which surrounds and protects cells. For this reason, bacterial biofilms cause chronic infections because they show increased tolerance to antibiotics.