Which of the Following Is True of Nitrogen

Which of the following is true of nitrogen?

A) N₂ is scarce in the atmosphere, therefore, plants must obtain other sources of nitrogen.
B) Animals require nitrogen from the food they eat for the synthesis of carbohydrates and lipids.
C) Nitrogen-fixing bacteria convert N₂ into compounds plants can utilize.
D) Nitrogen is plant food and, therefore, provides plants with energy.