Water molecules have the most kinetic energy when they are in the hydrosphere

Due to less inter molecular force of attraction.

Explanation:Hydrosphere consist of complete water mass on earth's surface that includes ponds, lake, oceans, underground water, glaciers and water over earth's surface that is clouds, etc.Water exist in three phases i.e Solid(ice), Liquid(water) and Gas(water vapors).Solid(ice) generally are rigid.They have definite shape and volume. Hence, their kinetic energy is smaller than that of loose fluids as their particles cant move freely.Liquid(water) is generally more free-form than solid but they still have a definite volume, as they aim to take the shape of their container in which they are kept.  The hydrogen-bonding in water makes the intermolecular forces more stronger, but inter molecular forces are not full bonds, so they are more free to move than of solids.Gases(water vapor) are free to move they neither have definite shape nor definite volume, they lack the inter molecular forces that hold liquids together, so they are more free to move than liquids.

Result: Water molecules in gas(vapor) phase in hydrosphere posses most kinetic energy.

Yeah, but what are you trying to ask?