Answer: c. renewable energy
The sources of renewable energy expected to increase in future because renewable resources are those resources which can be replenished after a single use such as water, sunlight and wind these are abundantly present in nature. The demand of nonrenewable resources is increasing day by day due to increase population and the global energy needs. The availability of these resources is decreasing as a result of this renewable resources are used as a source of energy. Like tidal energy, wind energy and solar energy used for the electricity generation by these resources going to fulfill the present as future energy needs.