Answer:
b. Nitrification
Explanation:
Nitrifying bacteria are present in the soil that help in the oxidation process of ammonia that liberates the nitrite (NO2-) and nitrate (NO3-) compounds. These resulting compounds are captured by plants and this process is called nitrification. In the nitrification stage there are two chemical processes. That are:
• Nitrous: is the oxidation of ammonia (NH3) that results in the nitrite chemical compound (NO2-).
• Nitration: It is the oxidation of ammonia (NH3) that results in nitrate (NO3-).