Viruses Are the Cause of Various Diseases Such as Polio

Viruses are the cause of various diseases such as polio, HIV, or the flu. However, viruses are also very helpful to our environment. In what way can viruses be beneficial to the environment?

A) Viruses caused the evolution of single-celled eukaryotes through horizontal gene transfer.
B) Viruses limit the bacterial infections in animals by causing mutations within the bacterial genome.
C) Viruses limit the number of viral infections in animals by mutating other viruses on contact.
D) Viruses limit the number of bacterial infections in plants by causing the mutations within the plant genome.
E) Viruses limit the number of other viruses and other microorganisms in soil and water.