50.Some viruses can undergo latency, the ability to remain inactive for some period of time. Which of the 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 or emotional 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