Inorganic diet bad to your well-being

Pia cried a suppressed "Ungghh!" and then went over to the sofa and sat down.  She was holding a dismantled leg of a toy plastic food cart.

Daddy:  What's wrong?

Pia: Nothing

Daddy: (wanting to take a look) Can you come here?

Pia comes over. She has blood on her lower lip and on the wrist of her shirt, apparently from wiping blood from her lip.

Daddy: Why is there blood on your lips?  You cut your lip!  How did that happen?

Pia: (showing the leg of the toy cart) I bit this.

Daddy: (??) Why did you bite it?

Pia: I don't know.

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