What keeps time inside Tock the dog?

• A. A wind-up mechanism in his tail
• B. A ticking heart
• C. A clock inside his body
• D. An internal sundial

Answer: (C)

In The Phantom Tollbooth, time is treated as a tangible thing that can be carried inside someone. Tock the dog is the living embodiment of time, with a clock literally inside his body that keeps time and helps the travelers know how much time has passed. That internal clock fits his role as a watchful guardian of time and explains why he’s always aware of the hours.

The other ideas don’t fit the world of the story: a wind-up mechanism in his tail would be external and mechanical, a ticking heart isn’t how he tracks time in the tale, and an internal sundial would depend on sunlight and isn’t a feature of a living clock. So the clock inside his body is the best answer because it aligns with how Tock is portrayed and how time works for him.