A centrifugal pump is fully primed, but on starting it fails to deliver fluid. The probable reasons are listed below:
1. Leaky foot valve or suction line
2. Suction head is very low
3. Insufficient motor speed
4. Damaged or closed delivery valve
Which of these reasons are correct?
(A) 1, 2, 3 and 4 (B) 1, 2 and 3 only
(C) 2, 3 and 4 only (D) 1, 3 and 4 only