Question

How can we say that environment is our basic life support

Answer 1

it gives us fresh and natural air

Answer 2

Environment consist of various other terms within itself like resources which include water, air, trees etc. We all living creatures are dependent on these resources. We can't live without any. If any resource will be exhausted after seeing such a vast use of them by humans then our life would come to an end. So they should be used wisely and are our basic life support. So environment is our basic life support and it should be preserved.