Answer
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Work Step by Step
a) Bacteria are orders of magnitude larger than viruses. Bacteria can be seen using light microscopes while viruses cannot (They need electron microscopes). They also satisfy all the criteria of a living organism while viruses satisfy most but not all. Some viruses even infect bacteria (called bacteriophage).
b) Yes, another approach is by using bacteriophages to target those bacteria. This was an approach that was championed by the Soviet Union and their troops.