My answers were polite one or two syllable replies , hoping that he would get the hint . He did not . So he chatted on for about 5 mins before he finally caught on and the conversation died away . I reached Bukit Merah at 8 am so I had some choice of seating . The earlier birds had all occupied the back rows and the next available empty seat was about mid way of the auditorium .

Question: What can plausibly be the hint to which the author makes reference in the paragraph ?
Answer: None of the above choices .The author most likely means that the speaker should have sensed that they were upset about something .The author was hoping that the speaker would understand that they wanted to sit in a different seat .The author is alluding to the notion that they wanted to be left undisturbed by strangers while t travelling .