To which cycle is guano an important component? 

A)  the phosphorus cycle 
B)  the carbon cycle 
C)  the hydrologic cycle 
D)  the sulphur cycle

Guano is a valuable fertilizer because it is rich in phosphorus. Phosphorus plays a vital role in many biological processes, including photosynthesis, cell division, and energy production. In the phosphorus cycle, guano is decomposed by bacteria and fungi, releasing phosphorus into the soil. The phosphorus then becomes available for uptake by plants, which are then consumed by animals. The cycle continues as the animals defecate and return the phosphorus back to the soil.