Which feature would you use to ensure an object snaps to exact grid lines as you position it?

The feature that allows an object to align precisely with a predefined grid is "Snap to grid." Using this feature ensures that when you are moving or positioning an object, it will automatically align with the grid lines you have set in your workspace. This is particularly useful for maintaining a consistent layout and ensuring that the elements in your animation are evenly spaced and aligned neatly, which can enhance the overall aesthetics and organization of your project.

The other features mentioned serve different purposes. "Snap to guideline" allows objects to align with guidelines that you have manually placed, providing flexibility but not necessarily the structured placement offered by a grid. "Snap to pixel grid" is useful when working with raster graphics where you want to ensure that the edges of objects align with the pixel grid, which helps avoid blurriness in bitmap images. "Snap to object" facilitates alignment with other objects in your scene, which is great for arranging elements relative to one another, but doesn't involve a grid system.