A dog uses its tongue to drink. A robin holds a branch with its feet. A chimpanzee digs for termites with a stick. A worm moves to the top of flooded ground.
Which is a learned behavior?

Options:
- A dog uses its tongue to drink.
- A robin holds a branch with its feet.
- A chimpanzee digs for termites with a stick.
- A worm moves to the top of flooded ground.

A chimpanzee digs for termites with a stick.