Which term describes the action of disgorging an undigested pellet?

The correct term for the action of disgorging an undigested pellet is "to cast." In falconry and wildlife biology, birds of prey often produce pellets that consist of indigestible materials such as bones, fur, and feathers from their prey. This process of ejection is known as casting, and it typically occurs several hours after the bird has eaten.

Casting is significant in understanding a bird's diet and health, as it reveals what the bird has consumed and provides insights into its feeding habits. The term encapsulates the physical act of the bird expelling these pellets, which is a natural and necessary behavior for many raptors. Other options do not pertain to this specific biological action, which differentiates casting from any unrelated concepts.