One condition that is required for viruses to reproduce is that they must be located within living cells.
When a virus is outside a living cell, it is not active and can not carry out any life process, but immediately it enters a living cell, it becomes active and cause the host cells to reproduce thousands of identical virus offspring at a very rapid rate.
The answer to your question is D. reliability !
hope this helps :^)
No. Microscopic organisms are not called phytoplankton, the are called microorganisms.
Factors in an enviroment change so species also need to evolve