Concept:Smallpox is a viral disease preventable by vaccination.Explanation:Smallpox is caused by a virus, not bacteria, so Option A is wrong.Antibiotics are ineffective against viruses, so Option B is wrong.Vaccination effectively prevents and controls smallpox and led to its global eradication, so Option C is correct.Smallpox is not spread through water, so Option D is wrong.Answer:C. It can effectively be controlled by vaccination