50.Some viruses can undergo latency, the ability to remain inactive for some period of time. Which ofthe following is an example?
(A) influenza, a particular strain of which returns every 10-20 years
(B) herpes simplex viruses (oral or genital) whose reproduction is triggered by physiological oremotional stress in the host
(C) Kaposi's sarcoma, which causes a skin cancer in people with AIDS, but rarely in those not infected
(D) the virus that causes a form of the common cold, which recurs in patients many times in their lives
(E) myasthenia gravis, an autoimmune disease that blocks muscle contraction from time to time