B. Viruses can multiply only when they are inside the living cells.
C. Viruses cannot pass through bacterial filters.
D. Viruses are made up of protein and DNA or RNA (never both DNA and RNA).
Correct Answer : C.
Virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses can pass through bacterial proof filters as they are smaller than bacteria.