What is the definition of a sprain?

A sprain is defined specifically as an injury to a ligament, which is the connective tissue that connects bones at a joint. When a ligament is overstrained or stretched beyond its limits, it can result in pain, swelling, and instability in the affected joint. This makes the definition of a sprain closely tied to the overstraining of ligaments, as provided in the correct response.

When considering the context of a sprain, it's important to clarify the distinction between ligaments and other tissues, such as muscles, to understand why this definition stands out. While muscles can be strained, such an injury would not be classified as a sprain but rather as a strain. The correct response thus captures the essence of the injury, pointing directly to the nature of a sprain as an ailment involving ligaments.