C.

quantity

The distribution of natural resources depends upon number of physical factors like terrain, climate and altitude.

The distribution of resources is unequal because these factors differ so much over the earth.

Using resources carefully and giving them time to get renewed is called resource conservation.

We should use resources in such a balanced way that we satisfy our needs as well as conserve them for future. This concept is called sustainable development.

People are human resources. People can make the best use of nature to create more resources when they have the knowledge, skill and the technology to do so. That is why human human resources are important