With strictFunctionTypes, which assignment is safe for function-property callbacks?

With strictFunctionTypes, which assignment is safe for function-property callbacks?

1. Assign (dog: Dog) => void where (animal: Animal) => void is required.
2. Assign (animal: Animal) => void where (dog: Dog) => void is required.
3. Both directions are always safe because Dog extends Animal.
4. Neither direction is allowed under strict mode.