Why are bacteria needed in the nitrogen cycle?

Bacteria help the nitrogen change between states.

Explanation:

When nitrogen is absorbed, bacteria helps change its state so it can be absorbed by different organisms.

The most important part of the cycle is bacteria. Bacteria help in the nitrogen change between states so it can be used . When nitrogen is absorbed by the soil , different bacteria help it to change states so it can be absorbed by plants. Animals then get their nitrogen from the plants.

b is the best answer for this question.