Which of the following is not a natural resource?

The most appropriate definition of a natural resource is that it is a substance/commodity that is

Though the kulhads are made up of clay,which is an eco-friendly substance,their use has been discontinued in trains nowadays. Give reasons which lead to the discontinuance of this practice.

What do the three $R$s refer to in order to save the environment? Which one of these would be the best for the environment?

State two main concepts of sustainable development.

On the basis of the issues raised in this chapter, what changes would you incorporate in your lifestyle in a move towards a sustainable use of our resources?