Renewable source of energy is _____ . Fill in the blank.
A) Coal
B) Fossil fuel
C) Natural gas
D) Sun

Hint:In order to answer this question you should know about the basic concept of renewable energy. Renewable energy sources are those which provide us with renewable energy. These energy sources are not depleted by use.

Complete step by step solution:
Here, as the name suggests renewable which means capable of being renewed. So, Renewable Energy Sources of energy are those which are not depleted by use, the examples are water, wind, sunlight etc.

Here, out of the four options given only sun is that kind of energy source which would not be depleted after use. Sun is perennial and hence, would never get exhausted by using its energy. The rest of the options say coal, fossil fuel, and natural gas; these all three get depleted by use. So, these energy resources are known as non-renewable sources of energy.

The energy sources that are renewed or which are replenishable in the human time scale are called renewable resources of energy. Hence, the Sun is naturally coming and can be used in the form of solar energy, to evaporate water which turns into rain and rains are useful in many uses. Hence, the Sun is the renewable source of energy.


So, option D is the correct answer.

Note: It is interesting to know that, Renewable resources are those energy sources that cannot be depleted and are also able to supply a continuous source of clean energy. Hence, energy from the sun is completely clean and does not cause any pollution, so it is a boon for our environment.