If there is certain virus that attacks a cells mitochondria, what would happen to the cell?

 An animal cell would die within a minute. Animal cells need a steady supply of ATP to power the reactions of the cell, and anaerobic fermentation won't supply enough to keep things going. 

Yeast, on the other hand, is not an obligate aerobe, and could survive without its mitochondria.

C. a mature ovule of a plant.