In the following question find out the alternative which will replace the question mark?
 

Light : Sun : : Heat : ?

Fire

The answer is Fire.

The analogy is between light and the sun, and heat and fire. The sun is the source of light, and fire is the source of heat. So, the missing word must be the source of heat. Of the answer choices, only fire fits this description.

The other answer choices do not fit the analogy. Electricity is a form of energy that can produce light, moon is a natural satellite that reflects sunlight, star is a celestial body that emits light, and Fiji is a country. None of these are sources of heat.