D. all of the above
Joint
Cartilage
Ossification
Marrow
Ligaments
Osteoporosis
Fracture
Simple fracture
Sprain
Dislocation
Smooth muscle
Cardiac muscle
Heart
Muscle tone
Tendon
Atrophy
Strain
Pulled muscle
Tendonitis
Central nervous system
Cerebrum
Cerebellum
Brain stem
Spinal cord
Reflex
Concussion
Coma
Paralysis
Seizure
Epilepsy