Which is a characteristic of a virus, but not a bacterium?
a) capsid
b) causes illness
c) damages the cells in a body
d) transmitted in food and drink

The best answer to the question above is letter C, damages the cells in a body. 
A virus is a  tiny organism which may lead to mild to severe illnesses in humans, animals and plants which includes flu or a cold to something more life threatening like HIV/AIDS.

Viruses cannot grow or multiply on their own. They are not alive, thus, they need to enter a human or animal cell and take over the cell to help them multiply. They can also infect bacterial cells.