‘S’ will be the first part of the given sequence as it is beginning the chronology of the event, that is, first the bus sped along the road( as stated in S1) and then a sudden event took place which is the coming of a stray dog onto the middle of the road. P will come next as the usage of ‘but’ here shows a contrast saying that since the bus was speeding up, therefore even after the dog came up in the middle of the road, then also the bus couldn’t stop suddenly as it could stop only after covering a few yards. ‘R’ will come next because it tells that driver applied the brake to save dog and ‘Q’ will come next because it tells the ultimate happening of non-stoppage of bus on time, that is, dog was injured in the leg. Hence, SRPQ is the right sequence. Thus, option (b) is correct.