Which of the following is a notable physical trait of the red-tailed hawk?

The reddish-brown tail is a distinctive characteristic of the red-tailed hawk, giving it its name and helping in identification. This trait is particularly prominent in mature adults and can vary in shade, but generally denotes the species. The tail's coloration serves as an important feature for bird watchers and ornithologists, as it can help distinguish the red-tailed hawk from other similar raptors in the field.

The other traits do not accurately reflect the key characteristics of the red-tailed hawk. Long tail feathers are not exclusive to this species and can be found in various hawks. A white head and tail describe other species, like the bald eagle, while bright yellow beaks are characteristic of several raptors, but not specifically the red-tailed hawk, which has a more muted bill color. Thus, the reddish-brown tail is a definitive marker that makes the red-tailed hawk easily recognizable among other birds of prey.