Answer: Reservoir
The reservoir is a component of the biosphere that serves as a long term storage unit for the nutrients or the water. It is a storage space for fluids. These fluids may include gas, hydrocarbon, and water. The reservoirs can be created artificially by controlling the stream that drains into the water body. It can also be constructed by building walls and levees. The underground reservoirs are used to store liquids like water or petroleum.
Hence, the correct answer would be Reservoir