An example of a pathogen that undergoes rapid changes resulting in antigenic variation is A) the influenza virus, which expresses alternative envelope proteins. B) the strep bacteria, which can be communicated from patient to patient with high efficiency. C) human papilloma virus, which can remain latent for several years. D) the causative agent of the autoimmune disease known as rheumatoid arthritis. E) multiple sclerosis, which attacks the myelinated cells of the nervous system.