A motorcyclist starts from the bottom of a slope of angle 45º to cross the valley PR as shown in the figure. The width of the valley is 90m and length of the slope is 80√2 m. The minimum velocity at point O required to clear the valley will be
(a) 70m/s
(b) 30m/s
(c) 50m/s
(d) 100m/s
