Biology

The correct answer is A.nitrification.

Nitrification is the process by which certain bacteria in the soil convert ammonia (NH₃) or ammonium (NH₄⁺) into nitrates (NO₃⁻), which are a more usable form of nitrogen for plants.

Here’s what the other terms mean:

B.Assimilation: This is the process by which plants absorb nitrates or ammonium from the soil and incorporate them into their tissues for use in proteins and other essential molecules.