private → visible only inside the same class.
default (no keyword) → visible inside the same package only.
protected → visible inside the same package + visible in all subclasses (even if in a different package).
public → visible everywhere.
private protected → ❌ Not a valid keyword in Java.
We want a member of a class visible in all subclasses, regardless of the package.
✅ That’s exactly what protected does.
(b) protected