The correct option is A Overstretching of ligament
A sprain is a stretching or tearing of ligaments which are the tough bands of fibrous tissue that connect two bones together in the joints. The most common causes of sprains are falling, twisting etc. These types of injuries may cause the joint to move out of its normal range of movement that causes the tearing or stretching of the ligament. So, the correct answer is 'Overstretching of ligament'.