Two trains A and B are moving on same track in opposite direction with velocity 25m/s and 15m/s respectively. When separation between them becomes 225 m, drivers of both the trains apply brakes producing uniform retardation in train A while retardation of train B increases linearly with time at the rate of 0.3 m/s3. The minimum retardation of train A to avoid collision will be
(a) 2 m/s2
(b) 2.5 m/s2
(c) 2.25 m/s2
(d) 2.75 m/s2
