What is the biggest social lack in Margie's machine education?

Correct answer: Lack of learning with classmates

The governing concept is the social impact of technology on education. Margie receives lessons from a mechanical teacher in her home, so her learning is efficient and individually adjusted, but she studies alone. She does not share a classroom, activities, discussions, or ordinary childhood experiences with classmates. Therefore, option B is correct: the major social lack is the absence of learning with other children. Immediate assessment, a home schoolroom, and telebook lessons are features of the system, but they do not identify its central social deficiency. The story suggests that technology may provide instruction while reducing companionship and classroom interaction.