What characteristic does 'fly back' describe in rabbit fur?

The term 'fly back' in rabbit fur specifically refers to the quick return of the fur to its original position after being stroked. This characteristic is an important quality in evaluating the overall condition and health of the rabbit's coat. When stroked, fur that has good fly back will spring back into place rather than stay flattened, indicating that the guard hairs—those that protect the undercoat—are healthy and well-structured. This property is desirable as it reflects the vitality of the rabbit and the quality of its fur. A coat with excellent fly back is usually associated with proper grooming, feeding, and overall rabbit care.

In contrast, the other options do not accurately define 'fly back'. The ability of fur to remain flat against the body refers to a different trait that is not indicative of healthy fur. Unusual softness represents a texture characteristic but does not relate to how the fur behaves when interacted with. The tendency of fur to become tangled addresses issues of grooming and coat maintenance rather than the fundamental property of fly back. Thus, the correct response encapsulates a specific and vital aspect of rabbit fur care and examination.