Tommy's role is important not merely as a companion but as what?

Correct answer: As a character who introduces past education

The governing idea is the narrative function of a character. Tommy discovers a real printed book and explains to Margie that children once studied together with a human teacher in a school building. Through his conversation with her, the reader receives important information about the contrast between old education and the computerized lessons of 2157. He is therefore more than a friend or companion: he helps introduce the past system of education and makes Margie imagine its social pleasures. Option A is correct. He did not design the mechanical teacher, he does not teach Margie formally, and he has no role as the County Inspector's assistant.