The conversion of nitrogen gas to ammonia is called

a. Denitrification

B. Nitrogen cycle

C. Nitrogen Fixation

D. Nitrogen limitation

C

Explanation:

Step 1 Nitrogen Fixation - Special bacteria convert the nitrogen gas (N2) to ammonia (NH3) which the plants can use. ∎ Step 2 - Nitrification - Nitrification is the process which converts the ammonia into nitrite ions which the plants can take in as nutrients.