Which adage best describes the paragraph?

Cara writes in her journal every day. While she’s thinking about what she wants to write, she chews on the cap attached to the top of her pen. She leaves chewed-up pens all around the house. Her family thinks it’s an awful practice. Cara has tried to stop, but she finds herself mindlessly chewing on the cap of her pen every time she stops to think while writing.

A.
Live and let live.

B.
If the shoe fits, wear it.

C.
Once bitten, twice shy.

D.
Old habits die hard.