A large cylinderical tank of cross-sectional area `1m^(2)` is filled with water . It has a small hole at a height of 1 m from the bottom. A movable piston of mass 5 kg is fitted on the top of the tank such that it can slide in the tank freely. A load of 45 kg is applied on the top of water by piston, as shown in figure. The value of v when piston is 7 m above the bottom is `(g=10m//s^(2)`)
(a). `sqrt(120)m//s`
(b). `10m//s`
(c). `1m//s`
(d). `11m//s`