Natural selection allows nature to chose which species survives. Only the fittest get to pass on their genes. And by fittest i mean the ones that are better adapted to the environment.<span />
This is a difficult question to answer with the given information...could you add more
recover she gets sick again. She also has a very stressful work and family life. What is most likely the cause of Chelsea's constant illness?
decreased lymphocyte production due to chronic stress
