What menu option is used to apply an elliptical mask?

The use of an elliptical mask in Adobe After Effects is achieved through the menu option that involves creating a new mask specifically intended for that purpose. By navigating to Layer > Mask > New Mask, the user establishes a new mask on the selected layer. Following this, accessing Layer > Mask > Mask Shape allows the user to modify the mask shape. The final step, selecting "Reset to Ellipse," converts this newly created mask into an elliptical form.

This process provides the necessary controls to customize the mask according to specific requirements, allowing for greater flexibility in how the effect is applied to different layers. It highlights the program's capability to manipulate mask shapes directly, making it a powerful tool for compositing and effects work.