According to Tommy, what were teachers like in the old times?

Correct answer: They were human beings

Tommy explains that the teachers in the old schools were human beings. This detail creates the central contrast in the story: children of Margie's time learn individually from mechanical teachers at home, whereas earlier children went to a school building and were taught by a person. Thus, option C is correct. A telebook is a device or electronic reading source, not a teacher. A machine teacher belongs to Margie's futuristic period, so option B reverses the time reference. A room is merely a place and cannot be a teacher, which makes option D illogical. The governing idea is the contrast between human instruction in the past and automated instruction in the future.