Which of the Statements About Biofilms Is True

Which of the statements about biofilms is true?

A) Biofilms are very rarely involved in human bacterial infections.
B) Biofilms may protect organisms against harmful chemicals.
C) Biofilms are a peptidoglycan-encased community of microorganisms.
D) Biofilms may significantly inhibit bioremediation efforts.
E) Biofilms are very seldom found in a natural environment.