Which method is used to bake lighting for static objects in Unity?

Baking lighting for static objects in Unity is accomplished through the use of lightmaps. This process involves pre-calculating the illumination of static surfaces in a scene and storing this information in textures known as lightmaps. These lightmaps capture the baked lighting, including indirect lighting and shadows, allowing for more efficient rendering during runtime.

By employing lightmaps, the rendering engine doesn't have to calculate lighting in real-time for every frame, which significantly enhances performance, especially in complex scenes with many static elements. This is particularly important in scenarios where maintaining high frame rates is crucial, such as in games or interactive applications.

In contrast, the other methods listed do not pertain to baking lighting for static objects. Audio mixers are concerned with managing sounds, light sources are used for dynamic lighting in the scene, and input managers deal with user inputs from devices like keyboards and controllers. These are all important components in a game development context, but they do not relate to the specific task of baking lighting for static objects. Therefore, lightmaps serve as the definitive solution for this purpose in Unity.