Final answer:
Groundwater is the reservoir of the hydrosphere that contains the largest fraction of Earth's liquid freshwater.
Step-by-step explanation:
The reservoir of the hydrosphere that contains the largest fraction of Earth's liquid freshwater is groundwater. Groundwater is found in the pore spaces and fractures in rocks and sediments. It is the largest reservoir of usable fresh water and contains more than 30 times the water found in rivers and lakes combined.