What are the biotic forms of nitrogen in the cycle

Biotic forms of nitrogen in the cycle:

Plants take in nitrogen

Animal eats the plant.

Animal is eaten by the secondary consumer.

The nitrogen is present in the chlorophyll, DNA and proteins.

Explanation:

In nitrogen cycle, nitrogen is converted into chemical forms. It is transferred  to organisms in the soil then back to the atmosphere. The nitrogen cycle involves nitrogen fixation in its cycle with the help of nitrogen-fixing bacteria. they form nitrites, nitrates and ammonia and are used by the plants consequently by animals and cycle goes on. Human do not use nitrogen directly.

i believe the correct answer is d