A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.
Adherence to the intestinal lining by this bacterium is due to its possession of
a) fimbriae.
b) pili.
c) a flagellum.
d) a capsule.
e) a cell wall with an outer lipopolysaccharide membrane.