Biofilms ________. (Select All That Apply)

Biofilms ________. (Select all that apply)

A) are a complex community of microorganisms that adhere to a solid surface via a matrix
B) may have one organism's waste products serving as a primary nutrient for another microbe
C) have aerobic microorganisms living near the top of the biofilm that use enough of the oxygen to make the lower layers either microaerophilic or anaerobic
D) are formed by all different species of bacteria