What feature would you use to fill areas of an illustration quickly?

The Live Paint Bucket Tool is designed specifically for filling areas of an illustration quickly and efficiently. This tool allows users to apply colors and patterns to specific regions of a drawing, even if those regions are not completely closed shapes. When using the Live Paint Bucket, you can hover over different areas of your artwork, and the tool intelligently detects and highlights the regions that can be filled.

Once you select a color, simply click on the desired area, and it will fill that section accordingly. This functionality is especially useful in complex illustrations where multiple overlapping shapes exist, as it simplifies the process of adding color.

In contrast, the Gradient Tool is meant for creating gradient fills rather than filling areas directly, which makes it less effective for quick area fills. The Shape Builder Tool allows you to combine or subtract shapes, which is not its primary function for filling. The Eyedropper Tool is used to sample colors from existing artwork but does not fill areas on its own. This is why the Live Paint Bucket Tool is the most suitable choice for quickly filling areas in illustrations.