Final answer:
The statement is false; phosphorous cycles through both the geosphere and the hydrosphere as part of Earth's natural processes.
Step-by-step explanation:
The statement that phosphorous ONLY returns to the geosphere (rocks) and not the hydrosphere (water) is false. Phosphorus, occurring naturally as the phosphate ion (PO4³-), cycles through both the geosphere and the hydrosphere. Weathering and volcanic activity release phosphate from rocks into the soil, which can then make its way into water bodies via surface runoff, groundwater flow, and river flow. Phosphate is an essential nutrient that enters marine ecosystems, where it is absorbed by organisms. It can then precipitate to the ocean floor, becoming part of the sediment. Over geologic time, movements of the Earth's surface can uplift these sediments, turning them into new landforms and completing the cycle back to the geosphere.