20. Which of the following statements regarding viral diseases is false? (A) Very few new human diseases have originated in other animals because the genetic differences are too great. (B) AIDS was around for decades before becoming a widespread epidemic. (C) RNA viruses tend to have an unusually high rate of mutation because their RNA genomes cannot be corrected by proofreading. (D) Some new viral diseases arise as a result of a mutation of existing viruses. (E) New viral diseases often emerge when a virus infects a new host species.