With reference to manometric head which of the following statements is correct?

• A. It is the head developed by the pump.
• B. It is the height to which water is lifted by the pump measured above the pump centreline.
• C. it is the difference in elevation between the water surface in the high level reservoir and the water level in the sump.
• D. It is the difference in the piezometric heads between the points on the delivery and suction pipes as close to the pump as possible.