A) the conversion of nitrate (NO₃⁻) into nucleic acids B) the incorporation of ammonia (NH₃) into amino acids C) the release of ammonia (NH₄⁻) from decomposing organic material D) the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) E) the conversion of ammonia (NH₃) into ammonium ion (NH₄⁺)