'S' will be the first part of the given sequence as the given part makes a logical pairing with 'when'. 'Q' will follow next because 'by a speeding car' is used in connection to 'be run over' in 'S'. It will then be followed by 'P' because it states that the boy saved the girl who was about to be run over by the speeding car. 'R' will be the last part as the pronoun 'his' is used in relation to 'a boy' in P. Hence, SQPR is the correct sequence. Thus, option (c) is correct.