Which effect of the machine teacher is negative in the story?

Correct answer: It can make the child feel lonely

The governing idea is that technology can make education efficient but may reduce human contact. In the story, Margie studies alone at home with a mechanical teacher, so she has no classmates with whom to share questions, activities, or the pleasure of learning together. This isolation makes her feel lonely and causes her to imagine that old schools were more enjoyable. Therefore, option A correctly identifies the negative effect. Options B, C, and D describe functions or advantages of the machine teacher, not its emotional drawback. The contrast between convenience and companionship is central to the story.