Answer: D) Nitrogen gas (N2) is so stable that only a few organisms are capable of turning it into nitrogen that can be used for living things.
Step-by-step explanation:
Nitrogen cycle is very important for the growth and development of the plants. This is because of the fact that nitrogen being in the form of nitrogen gas in the atmosphere cannot be absorbed by the plants readily instead it should be converted into forms which can be utilized by the plants. Only few organisms particularly some strains of bacteria can perform the task of nitrogen fixation in the soil.