Which are the three main categories of joints based on their degree of movement?

• A. Fibrous joints, cartilaginous joints, synovial joints
• B. Hinge joints, pivot joints, ball-and-socket joints
• C. Solid joints, movable joints, immovable joints
• D. Fibrous joints, synovial joints, gliding joints

Answer: (A)

Joints are categorized by how much they move: fibrous joints are essentially immovable, cartilaginous joints allow only limited movement, and synovial joints are freely movable. This framing explains the three main groups: fibrous joints connect bones with dense connective tissue and show little to no motion (like sutures in the skull), cartilaginous joints use cartilage to join bones with some give (such as the joints between vertebrae), and synovial joints have a fluid-filled capsule that enables a wide range of movement (examples include the knee, elbow, and shoulder).

That’s why the best choice lists fibrous joints, cartilaginous joints, and synovial joints. The other options mix different ideas: hinges, pivots, and ball‑and‑socket are specific shapes or types within the movable synovial category, not a broad movement-based grouping; another option uses terms like solid or immovable that aren’t standard classifications by movement; and gliding joints are a subtype of synovial joints, not a separate category by movement level.