Which of the following is NOT a natural resource?
a. a metal ore in the ground for which there is currently no use
b. trees in a remote part of the Amazon rain forest
c. a beautiful species of butterfly that naturalists and photographers enjoy observing in its native habitat
d. sand and gravel used in highway construction
e. an urban park

Option (C)

Explanation:

Natural resources are usually defined as those resources that are found to be distributed on earth and that also helps in building up the economy. This includes the trees in the forests, economic minerals, water, soil, and air.

In the given options, the metal ores, trees, economic minerals, and the parks are all an example of natural resources, as, from these resources, the economy of the country can be enhanced.

Whereas, the butterflies are not considered to be a natural resource because they are beautiful and it commonly attracts the people, such as the naturalists and the photographers, but there is no gaining of the economy here.

Thus, the correct answer is option (C).