Answer: The correct option is C) Nitrogen.
Nitrogen ( N₂) is the most prevalent gas in the atmosphere. It contributes 80% in the atmosphere. It is a highly stable gas because it contains three bonds between the two nitrogen atoms. So, it requires high energy to break these chemical bonds.
Nitrogen is the basic nutrient for the survival of all life forms. It is present in bio-molecules like proteins and DNA.
Nitrogen gas can not be used as such by the plants and animals. Therefore, it is converted into other forms so that plants and animals can utilize it. The process of conversion of N₂ into other biologically available form is termed as Nitrogen fixation.