Why do scientists consider hiv to be an emerging virus? a) hiv infected humans long before the 1980s, but it has now mutated to a more deadly form. b) hiv mutates rapidly making the virus very different from hiv in the early 1980s. c) hiv suddenly became apparent and widespread in the 1980s. d) hiv is now starting to cause diseases other than aids, such as rare types of cancers and pneumonias.