Concept:Lightning provides the energy needed to convert atmospheric nitrogen into compounds that enter the nitrogen cycle.
Explanation:When lightning strikes, its high temperature breaks the strong bond in atmospheric
N2 molecules.
The nitrogen atoms combine with oxygen to form nitrogen oxides such as
NO and
NO2.
These nitrogen oxides dissolve in rainwater to form nitric acid,
HNO3.
The acid falls to the ground and deposits nitrates,
NO3−, in the soil.
Plants and other organisms can then absorb these nitrates for growth.
Plant uptake and absorption of mineral salts only remove nitrogen from the soil, not release it into the atmosphere.
Complete breakdown of sugar releases carbon dioxide and water, not nitrogen gas.
Therefore, the process linked to nitrogen being released into the atmosphere among the options is lightning strike.
Answer:D. when lightning strike.