Having excellent hearing Living six to seven years Dropping nuts in front of cars Having black feathers
I gave my students this multiple choice question: Crows are found throughout many parts of the world. They are black birds with excellent hearing. In the wild they live for six to seven years. Some crows in Japan open hard-shelled nuts by dropping them in front of moving cars. Which of these is a learned behavior?

Only one answer is correct among these 4 choices:
- Having excellent hearing
- Living six to seven years
- Dropping nuts in front of cars
- Having black feathers

Could you tell me which one is correct?

Dropping nuts in front of cars