What is a characteristic of ligaments?

Ligaments are indeed characterized by their role in connecting two bones or cartilages. They are tough, flexible bands of connective tissue that help stabilize joints by holding bones together, thereby providing support and facilitating movement. This connection is crucial for maintaining the structural integrity of the skeletal system, allowing for a range of motions while also preventing excessive movement that could lead to injuries.

The other options describe different aspects of musculoskeletal anatomy. For instance, attaching muscles to bones refers to tendons, not ligaments, which have a different function in the body. Providing insulation to muscles is not a role of ligaments; that function is related to adipose tissue and other structures designed for thermoregulation. Meanwhile, containing muscle fibers for contraction pertains specifically to muscles and not to ligaments, which do not have muscle fibers and are not involved in contraction. Thus, the defining role of ligaments in connecting bones or cartilages makes the choice that specifies this characteristic the correct answer.