An aeroplane is flying at a height of 1960 m in horizontal direction with a velocity of 360 km/hr. When it is vertically above the point. A on the ground, it drops a bomb. The bomb strikes a point B on the ground, then the time taken by the bomb to reach the ground is
(a) 20√2 sec
(b) 20 sec
(c) 10√2 sec
(d) 10 sec