OPTIONS: +major threat to health. +h2o. +simplest known organisms. +Food poisoning. +mercury. +humans. +By wind and rain. +microorganisms.
Given those answer options, answer the question: Fact 1: Viruses often infect bacteria. Fact 2: Viruses Viruses are the simplest organisms known. Given the two facts above, what often infects bacteria?
A:
simplest known organisms