Which of the following disease agents can be identified based on the original form of koch's postulates? a. tay-sachs disease is caused by a genetic mutation in the hexa gene. b. acquired immunodeficiency syndrome, known to only occur in humans, is caused by human immunodeficiency virus. c. infectious mononucleosis is caused by the obligate intracellular parasite epstein barr virus. d. tuberculosis, which can be studied in both mice and humans, is caused by the bacterium mycobacterium tuberculosis.