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In the nitrogen cycle, what process involves the incorporation of nitrogen into organic compounds?

  1. Nitrogen fixation

  2. Nitrification

  3. Assimilation

  4. Denitrification

The correct answer is: Assimilation

Assimilation is the process where nitrogen is incorporated into organic compounds. Nitrogen fixation (option A) involves converting nitrogen gas into a form usable by plants. Nitrification (option B) is the process of converting ammonia into nitrate. Denitrification (option D) is the process of converting nitrates back into nitrogen gas. These processes all play a role in the nitrogen cycle, but they do not involve the incorporation of nitrogen into organic compounds. Therefore, option C is the best answer.