Is often a major part of fertilizers since the plant cannot usually produce (or obtain) sufficient amounts.

Nitrogen would be a major part o fertilizers. If you remember the Nitrogen fixation cycle there are organisms who hold the purpose of fixing Nitrogen to go back into the soil and atmosphere.

The correct answer is a. we know this because n (hap) + n (hap) = 2n (dip).

To kill bacteria from our body especially from stomach