Genetic Change in Viruses. Viruses are continuously changing as a result of genetic selection. They undergo subtle genetic changes through mutation and major genetic changes through recombination. Mutation occurs when an error is incorporated in the viral genome
        
             
        
        
        
Very true.
It harms our atmosphere, thus effecting climate. Which can kill and sometimes nearly cause organisms to go extinct. It corrupts our air, which is very unhealthy, and can cause lung cancer, and harm our breathing patterns. Which can shorten life expectancy.
Stay clean, and I hope this helps! :) <span />
        
             
        
        
        
Cellular respiration, on the other hand, is the process by which living things convert oxygen and glucose to carbon dioxide and water, thereby yielding energy. It does not require the presence of sunlight and is always occurring in living organisms. Cellular respiration takes place in the mitochondria of cells.
        
             
        
        
        
The correct answer is B, I know this because none of the other answers are even reasonable. For example-
A is wrong because the size of elephant tusk has not changed over time, elephant tusk just grow...
C is wrong because it makes no sense to hunt elephants with no tusk :/
D is completely wrong because tusk have nothing to do with reproduction, those are two completely separate bodily functions.........