Solar cells are devices which directly convert ________ into electric energy.
a)Heat energy
b)Mechanical energy
c)Chemical energy
d)Solar energy

Hint: In the above question we are basically asked how the energy conversion takes place in a solar cell. From the word solar itself we actually come to know it's related to energy from the sun. First we will see how a solar cell works. Further accordingly we will determine how the energy conversion takes place and select the correct alternative from those provided.

Complete step by step answer:
A solar cell is a device which can be used as emf i.e. driving force in electrical circuits. These consist of semiconductors. These semiconductors are doped such that one piece of the solar cell gets electron rich and the other electron deficient. Further these two pieces are joined together to form a p-n junction. When sunlight is incident on these solar cells, the electrons gain energy from the photons and move across the region such that one region gets positively charged and the other gets negatively. As a result of this, there is a potential difference generated which basically can be used as a battery or a cell to produce current is a circuit.
Since in this process there is direct conversion of energy from the sun i.e. solar energy to electrical energy.

So, the correct answer is “Option d”.

Note: Doping is a process of introducing impurities into the semiconductors. It is basically done in two ways i.e. introducing a electron deficient or electron rich impurity. The semiconductor i.e. used for making solar cell is silicon. Silicon is obtained from sand after many processes of purification.