Read the following passage and answer the question :

Use of Non-conventional sources of Energy : India, as you know, is hugely dependent on thermal & hydro power plants to meet its power needs. Both of these have adverse environmental impacts. Thermal power plants emit large quantities of carbon dioxide which is a green-house gas. It also produces fly ash which if not used properly, can cause pollution of water bodies, land & other components of the environment. Wind power & solar rays are good examples of non conventional cleaner & greener energy sources but they are not yet explored on a large scale due to lack of technological devices.

Thermal power plant uses _ _ _ _ _ _ _ _ _ to produce the thermal energy :

Coal

The correct answer is option (4) : Coal

This is implied in the passage, which discusses the environmental impacts of thermal power plants, such as the emission of carbon dioxide and production of fly ash, both of which are commonly associated with coal-fired power plants.