Option C, using nuclear power, is the right answer.
Conservation of resources is the humane consumption and safekeeping of precious resources, such as water, wildlife, minerals and trees etc. The main focus of the conservation of resources is on maintaining the physical environment in order to preserve the sources of supplies.
Options A, B and D, contribute to the Conservation of resources in one or another way. But option C (using nuclear power) does not contribute to resource conservation because of the elements used in the production of nuclear energy cannot be recycled.