The correct answer is "They lack an independent metabolism"
Explanation:
Viruses are usually active/alive in a living environment and become inactive in non-living environment; these is because they rely on the metabolic activities of the invaded living environment/cell. This property is a sharp contrast to normal living cells that are able to metabolize different substances independently using several organelles.
The sun has little or nothing to do with any of these answers except A. The sun gives plants energy, plants give animals energy, and animals give us energy. (Unless you're vegetarian in which case you skip the animal part)
