Concept:Viruses show living features only when they are inside a host cell.
Explanation:Outside a living cell, a virus is inactive and behaves like a non-living particle.
Inside a living cell, it can multiply by using the host cell's machinery.
This ability to reproduce only within living cells is why it can be regarded as a living organism.
Causing diseases, existing in different shapes, or being seen with an electron microscope are not special living features.
Therefore, reproduction in living cells is the correct living characteristic of a virus.
Answer:D. Reproduces in living cells