Why did Margie consider Tommy's discovery important in her diary?

Correct answer: Because a real printed book was rare

Tommy’s discovery was important to Margie because he found a real printed book, an object that was unusual and rare in their technologically advanced time. Margie was familiar with telebooks and moving words on a screen, so the paper book seemed strange: its words stayed fixed, and it described schools from the past. Therefore, option A is correct. Option B is wrong because Tommy did not invent a machine; he discovered an old book. Option C has nothing to do with the diary entry, and option D is not the reason for the discovery’s importance. This event begins the story’s comparison between traditional human schooling and isolated mechanical instruction.