Answer the following question: Fact 1: Viruses cause many human diseases. Fact 2: Some smallpox viruses are maintained in laboratories. Given the two facts above, what can smallpox cause?

Choose your answer from:
(1). contamination
(2). harmful substances
(3). vaccines
(4). photosynthesis
(5). extinction
(6). cellular respiration
(7). Destroy crops
(8). human disease
Answer:
(8).