question_answer

Ozone layer is made up of oxygen molecules and it is spread between 10 km to 50 km above the ground. We see mountaineers carrying oxygen cylinder and fighter pilots is bearing oxygen mask. Why they have to do so when there is already a layer of ozone above the ground?

A)  Because ozone is not useful for breathing

B)  Because layer of ozone is very high

C)  Because they do so for just precautions

D)  Because there is not sufficient ozone for breathing

E)  None of these