'P' will be the first part of the given sequence as it begins the narration of a man who if does not possess a good memory is regarded as eccentric. 'R' will come next as the pronoun 'he' is used in connection to 'father' mentioned in the very previous part. 'Q' will come next as it states what happened when the father left the perambulator outside and disappeared into the drink shop. 'S' will follow next as 'her' is used in connection to 'his wife' in 'Q'. Hence, PRQS is the correct sequence. Thus, option (b) is correct