You didn't really provide us with any options? It must be noted that generally, the structure of the skeletal system also dictates its function. With that I mean that having bones and a skeletal system enables us to move more efficiently and to have the pose which we have.
Answer:
age
Explanation:
the answer to this question is age
Head injury, as your head is your skull, damaging your skull is very serious as your brain is located there and damaging your brain could probably kill or limit some abilities
