The most appropriate definition of a natural resource is that it is a substance/commodity that is:
(a) present only on land
(b) a gift of nature which is very useful to mankind
(c) a man-made substance placed in nature
(d) available only in the forest
Natural resources occur naturally within an environment that exists relatively undisturbed by a human, in a natural form. A ‘natural resource’ is a substance/commodity of nature which is very useful to mankind. These are air, water, soil etc.
(a) These can be present anywhere, not necessarily only on land.
(b) These are a gift of nature which are very useful to mankind.
(c) These are not man-made substances.
(d) These can be present anywhere, not necessarily available only in the forest
Hence option (b) is correct.