A ten-year-old boy fell and hurt his ankle after landing on someone else's foot when coming down from a jump in basketball during summer camp. The camp physical therapist examined the patient and found moderate swelling of the lateral ankle with tenderness to palpation superior to the lateral malleolus. The patient has pain with ankle inversion both passively and actively and pain with weight-bearing. Which of the following structures should the physical therapist suspect is injured?

A. Anterior talofibular ligament
B. Anterior tibiofibular ligament
C. Fibula
D. Posterior talofibular ligament
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