Pick up the correct statement from the following regarding radial flow centrifugal pumps :

• These are provided with volute type or turbine type casings
• In involute type of radial flow centrifugal pump, the impeller discharges into a gradually expanding spiral casing
• In turbine type of radial flow centrifugal pumps, the impeller is surrounded by stationary guide vanes to reduce the velocity of water
• The efficiency of turbine type of radial flow centrifugal pump, is always higher than that of volute type
• All the above.