Viruses use the host cell to copy themselves and then viruses synthesize their own proteins manufacture their own atp, proteins, and nucleic acids metabolize food and produce their own atp use the host cell to copy themselves and make viral proteins

a.) a destruction fo cells by viral reproduction

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.