GENERAL KNOWLEDGE

Detailed explanation-1: -Answer and Explanation: The correct answer is D. By denitrification.

Detailed explanation-2: -The difference between nitrogen fixation and denitrification is that nitrogen fixation is the process in which converts molecular nitrogen to ammonia or other nitrogenous compounds. Denitrification is the opposite in that nitrates are reduced to produce molecular nitrogen.

Detailed explanation-3: -Nitrogen cycle is the circulation of nitrogen in the environment. The main difference between nitrification and denitrification is that nitrification is the conversion of ammonium into nitrate whereas denitrification is the conversion of nitrate into nitrogen gas.

Detailed explanation-4: -Denitrification. Denitrification is the process that converts nitrate to nitrogen gas, thus removing bioavailable nitrogen and returning it to the atmosphere. Dinitrogen gas (N2) is the ultimate end product of denitrification, but other intermediate gaseous forms of nitrogen exist (Figure 7).