Read this passage from The Phantom Tollbooth.

"Allow me to introduce all of us," the creature went on. "We are the Lethargarians, at your service." . . . .

"I'm very pleased to meet you," said Milo, not sure whether or not he was pleased at all. "I think I'm lost. Can you help me please?"

"Don't say 'think,' " said one sitting on his shoe, for the one on his shoulder had fallen asleep. "It's against the law." And he yawned and fell off to sleep, too.

Which phrase from the passage best helps the reader understand why the creatures are called “Lethargarians”?

A “We are the Lethargarians, at your service.”
B not sure whether or not he was pleased at all
C "Don't say 'think,' " said one sitting on his shoe.
D for the one on his shoulder had fallen asleep