Which of the following is a sign of an ankle sprain?

Localized swelling and bruising are characteristic signs of an ankle sprain. When an ankle sprain occurs, the ligaments that support the ankle are stretched or torn, leading to inflammation in the affected area. This inflammation often manifests as swelling around the ankle joint. Additionally, the damage to the small blood vessels in the surrounding tissues can cause bruising, which is also a common visual cue associated with this type of injury.

In contrast, increased flexibility, muscle tone improvement, and friction noise during movement do not indicate an ankle sprain. Increased flexibility might result from proper rehabilitation or conditioning but is not a symptom of an acute injury. Muscle tone improvement is related to strength and conditioning, which does not correlate with an injury like a sprain. Lastly, friction noise indicates joint issues unrelated to the typical signs of a sprain.