This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thigh, Knee,Leg,Foot & Ankle injuries, Subject name: Orthopaedics
A 23 year old profession footballer sufferd a twisting injury to his right ankle. On examination there is a lot of swelling around the medial malleolus but X-ray doesn't show any fracture. The structure injured could be- 
Select and explain. 
A. Deltoid ligament, B. Anterior talofibular ligament, C. Spring ligament, D. Tendo Achilles
A: Deltoid ligament
Answer: A: Deltoid ligament 
Explanation: * Swelling around medial malleolus suggests injury to deltoid ligament. Ref: Zhang C, Lin GM, Liu M. Progress of diagnosis and treatment in deltoid ligament injuries of ankle. Zhongguo Gu Shang. 2013;25 (11) : 967-70