What does Mr. Curtain use to control people's minds?

Mr. Curtain uses a device called the Whisperer to control people's minds. This device is central to the plot as it demonstrates the extent of Mr. Curtain's manipulative and sinister abilities. The Whisperer operates electronically to influence thoughts and actions, allowing Mr. Curtain to exert power over individuals without their consent or awareness. This mechanism also highlights the theme of control versus freedom throughout the story, where the characters strive to resist such manipulation. The other options, while plausible in different contexts of mind control, do not specifically depict the primary method used by Mr. Curtain in his schemes.