Beth learned in her science class that white blood cells in the human body capture harmful material by engulfing them then they digest them using enzymes does protecting the body from infection

ok, good for Beth, but where is the question??

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

bacterium is not correct