The bacteria Pseudomonas aeruginosa produces a protein that is secreted into its environment. The protein inhibits synthesis of elongation factor 2 (another protein) in humans. This effect may sound dangerous, but it has been considered as a possible treatment for hepatitis B. The protein produced by P. aeruginosa is a(n)
◦ biofilm.
◦ endotoxin.
◦ exotoxin.
◦ biological weapon.