What are two ways to move your background layer backwards in 3D space?

The correct choice involves two methods that effectively manipulate the position of a layer in 3D space within Adobe After Effects. By changing the Z position value, you directly alter the layer's positioning along the depth axis of the 3D environment. In After Effects, the Z-axis determines how far a layer is positioned away from or closer to the camera—negative Z values move the layer farther back in space, while positive values bring it closer.

Additionally, dragging the blue arrow, which represents the Z-axis in the 3D layer's transform controls, provides an intuitive, visual way of adjusting the depth of the layer. This method allows users to see the immediate impact of their adjustments within the composition, making it easier to achieve the desired spatial arrangement of layers relative to one another.

The other options, while they offer important functionalities, do not pertain specifically to moving a layer backwards in 3D space. Opacity affects visibility, rotation alters the layer's orientation rather than its position, and scaling changes dimensions, none of which can directly achieve the backward movement in a 3D context.