To synchronize multiple animations, you would use a _______ alongside multiple AnimationControllers.

To synchronize multiple animations, Flutter developers use the 'AnimationSync' alongside multiple AnimationControllers. The 'AnimationSync' class allows developers to coordinate the timing and execution of multiple animations, ensuring they work together seamlessly. This is particularly useful in scenarios where different parts of the UI need to be animated concurrently but in a synchronized manner. Understanding how to use 'AnimationSync' is crucial for implementing complex synchronized animations in Flutter.