Final answer:
Ammonia is an important chemical in the nitrogen cycle, contributing to nitrogen fixation and the production of fertilizers for agriculture. The correct answer is option b.
Step-by-step explanation:
It plays a key role as a substance through which nitrogen is made available to living organisms. The nitrogen cycle is integral for recycling nitrogen through the biosphere, and ammonia, with its chemical formula NH3, is a precursor for various nitrogen-containing compounds that plants and other organisms need for growth like proteins and nucleic acids.
In the nitrogen cycle, atmospheric nitrogen gas (N2) is converted into ammonia through a process known as nitrogen fixation. The ammonia produced can then be used directly by plants or further processed into nitrate or nitrite ions, which are also accessible forms of nitrogen for plant uptake.
Moreover, ammonia's role extends beyond the nitrogen cycle as it is also used in the production of fertilizers, which is crucial for the growth of agricultural crops such as corn and cotton. Thus, recognizing the centrality of ammonia in nutrient cycles is important for understanding ecological and agricultural systems.