Biology

The correct answer is: D.Assimilation.

Assimilation is the process in the nitrogen cycle where plants absorb ammonium ions (NH₄⁺) and nitrate ions (NO₃⁻) from the soil through their roots. These nitrogen compounds are then used by the plants to build important organic molecules such as DNA, amino acids, and proteins, which are essential for the plant's growth and development.

Here's a brief overview of the other processes for comparison:

A.Nitrogen Fixation – The process by which nitrogen gas (N₂) from the atmosphere is converted into ammonia (NH₃) or nitrate ions (NO₃⁻), typically by nitrogen-fixing bacteria or lightning. This makes nitrogen av...