Pick up the correct statement from the following :

• At a particular speed of operation, the head produced decreases with the increase of discharge
• At zero discharge, discharge valve remaining closed, the head developed is maximum which is known as shut-off head
• At a particular speed the discharge at which efficiency of a pump is maximum, is known as normal discharge
• The brake horse power required from the primemover to drive the pump, increases with the increase of discharge
• all the above.