What Advantageous Uses Have Viruses Been Shown to Have

Multiple Choice

What advantageous uses have viruses been shown to have?

A) The activities of viral genes mimic those of host genes so they are useful for studying mechanisms of DNA replication and gene expression in their much more complex hosts.
B) They can be used as a means to introduce foreign genes into human cells, which may serve as a basis for treatment of human diseases by gene therapy.
C) Insect-killing viruses may play an increasing role in the war against insect pests.
D) Bacteria-killing viruses may play an increasing role in the war against bacterial pathogens.
E) All of these are correct.