How does technology make alternative resources available?

Technology is the sustainable way to generate tha alternate new sources of energy and suffice the demand of earth's resources.

Explanation:

Coal and firewood is the only conventional sources of energy in the world since Industrial revolution. After introduced modern machineries, oil and natural gas were diggiong out using modern tools but these resources also exhaustable. So many countries and international organisations innovate the new technology and produce the renewable energy in the cost effective manner such as Solar energy, Wind energy, Biofuel and so on, they are not pollute the environment and generate sustainable earth for our future's  world.

d is the logical answer but im not a 100% sure