Nonrenewable resources
a are scarce.
b may become renewable resources as a result of technological advances.
c exist only in fixed amounts.
d are price controlled.

Option (C)

Explanation: Non renewable resources refers to those resources that cannot be regenerated after being used. This are also known as the conventional energy resources. They are formed from the decay of ancient planta and animals that were buried millions of years ago. For example, coal, petroleum, oil and natural gas.

This amount of this resources are present on the earth in a very fixed amount and have great economic significance. Since it is present in a very small amount, so it must be use carefully and if possible should make minimum use of it.

In order to sustain this resources, alternate renewable resources are being used.

Thus, the correct answer is option (C).

c, this answer is productivity.