Respuesta :
The right answer is B.
Nitrogen fixation is done by decomposers that are prokaryotes (bacteria).
Take the example of legumes.
The different species of rhizobia bacteria, which are able to infect the roots of legumes (Fabaceae family), are specific to certain host plants. Rhizobium phaseoli infects beans (Phaseolus sp).
Bacteria cause the formation of nodules on the roots by penetrating the root hairs, and transform into larger "bacteroids". The nodules are the seat of a symbiotic activity in which the plant provides the sugars and energy from photosynthesis, and in return benefits from the amino acids that are produced there.
The process of nitrogen fixation is carried out only by prokaryotic organisms, which have the ability to reduce nitrogen, where decomposers move nitrogen into the soil.
What is nitrogen fixation?
It is a process that involves the transformation of relatively unreactive atmospheric N2 into its more reactive compounds (nitrates, nitrites or ammonia).
Organisms capable of converting N2 to ammonium NH4+ naturally are decomposers such as some bacteria.
This allows inorganic nitrogen to leave the reservoir in the atmosphere and enter the soil or water (lakes, oceans), in a form that plants can use through their metabolism.
Therefore, we can conclude that the process of nitrogen fixation is carried out only by prokaryotic organisms, which have the ability to reduce nitrogen, where decomposers move nitrogen into the soil.
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