Answer: (D) Coal
Step-by-step explanation:
Yes, as compared to all the given options coal is one of the high polluting energy sources. The coal is the most polluting as when we burn the coal it cause acid rain, smog and the air pollution which is toxic and also harmful for the environment.
The coal plants typically produced 3.5 millions ton of the carbon dioxide (CO2) gas per year and then it lead to global warming. As compared to all other options, when it produced harmful gases per unit of energy then it is more harmful for the environment.
Therefore, Option (D) is correct.