Identify the non-conventional source of energy.

The correct answer is option (3) : Wind power

Conventional sources of energy are the sources that have been traditionally used on a large scale for a long time. They may be renewable or non-renewable, but they are part of the older and commonly used energy system. Examples: coal, petroleum, natural gas, thermal power, hydropower. Hydropower is renewable, but it is still classified as a conventional source because it has been used traditionally for many years on a large scale.

Non-conventional sources of energy are the newer and alternative sources of energy that are generally renewable, less polluting, and developed to reduce dependence on conventional sources. Examples: solar energy, wind energy, tidal energy, geothermal energy, biogas.