A sprain refers to the stretching or tearing of a ligament, which is a band of tissue that connects bones to each other and provides stability to joints. When a ligament is stretched beyond its normal range of motion, it can result in pain, swelling, and difficulty in moving the affected joint. In contrast, muscle tearing typically refers to damage to the muscle fibers themselves, while a sprain specifically involves damage to the ligaments. Therefore, the correct answer for this question is sprain.