Which characteristic is specific to true falcons?

True falcons are known for their distinctly "toothed" or "notched" beak, which is a notable anatomical feature that sets them apart from other birds of prey. This notch aids in the killing of their prey, allowing them to efficiently grasp and tear flesh. The presence of this unique beak structure is specific to the Falconidae family, giving true falcons an advantage when catching and consuming their primarily avian prey.

The other options describe characteristics that may apply to various types of raptors or birds more broadly but are not exclusive to true falcons. For instance, while some predators may possess strong feet adapted for crushing, this is not a defining trait for falcons. They are versatile predators and may feed on a range of animals, but their diet is not limited strictly to birds. Although many true falcons exhibit exceptional maneuverability while hunting, it doesn't completely define their nature in the way that the notched beak does. Therefore, the characteristic of having a "toothed" or "notched" beak is the most specific and distinguishing trait of true falcons.