Is my answer correct?
--> show details & explanation if i'm wrong<3

3- Nervous and Digestive

Explanation:

1: The nervous system works to alert the young birds of danger as the nervous system consists of different types of neurons and receptors, which enable the bird to feel pain or dainger. For example, if a predator was nearby and attacked the bird, the nervous system would help trigger a fight-or-flight response in the bird to help it survive.

2: The nervous system helps to produce vomit - vomit comes from the stomach, which is part of the digestive system, and bile and various other substances from the stomach will be pushed back up the oesophagus as the bird vomits, allowing it to protect itself.

Hope this helps, let me know if you have any questions! :)