Which is an example of a secondary energy source

Explanation:

Secondary energy resources are those which do not occur naturally but which are obtained from one or more of the primary energy resources. Example: Petrol or gasoline, electrical energy from coal burning, hydrogen obtained by electrolysis of water etc. Non-commercial source of energy: Firewood, cow dung , and vegetable wastes.

the answer would be d

is this for the e2020 class