A motor is used to deliver water at a certain rate through a given horizontal pipe. To deliver n-times the water through the same pipe in the same time the power of the motor must be increased as follows :

Question

$$\begin {array} {1 1} (a)\;n-times & \quad (b)\;n^2-times \\ (c)\;n^3-times & \quad (d)\;n^4-times \end {array}$$