The correct answer is C. Ammonia into nitrite.
Nitrification is the process by which ammonia is converted into nitrite and then nitrate by bacteria. This process is important in the nitrogen cycle, as it helps to convert ammonia, which is toxic to plants, into nitrates, which are essential for plant growth.
Ammonia is the simplest form of nitrogen and is the main form of nitrogen that is released into the environment from animal waste, sewage, and the decomposition of organic matter. Nitrifying bacteria convert ammonia into nitrite, which is then converted into nitrate by nitrate-oxidizing bacteria.
Nitrates are the most oxidized form of nitrogen and are the form of nitrogen that is taken up by plants. Nitrates are also the form of nitrogen that is most likely to leach into groundwater and surface water.
Nitrification is an important process in the nitrogen cycle, as it helps to convert ammonia, which is toxic to plants, into nitrates, which are essential for plant growth. However, nitrification can also lead to the release of nitrous oxide, which is a greenhouse gas.