What was the usual medium for reading books in Margie's time?

Correct answer: Telebook

The correct answer is A, telebook. In the futuristic setting of the story, people normally read words from a screen rather than from pages bound in a printed volume. Tommy's discovery of a real book is unusual to Margie because its words remain still and do not move or refresh like the material on a telebook. This detail establishes the technological world in which Margie lives and makes the old printed book a symbol of an earlier form of learning. A paper book, handwritten manuscript, or clay tablet is not presented as the usual medium in her time. The telebook therefore clearly fits the description.