Answer:
Number 1 and 4 are your best options. Although I am unsure of the answer, i hope this helped you narrow them down! good luck!
Vary from person to person!
Bones contain three components that in itself make it strong and flexible. They are collagen, calcium phosphate, and living bone cells. Collagen gives bones their structure, calcium makes bones strong, and cells generate more bone cells to fill up weakened parts. Calcium intake from food supplements and milk are also good for the bones because it can strengthen them more and make the skeletal system protected from bone irregularities and problems while growing. Vitamin D is essential for the absorption of calcium in bones. In order to offer support to the muscles and tissues of the body, bone growth is very crucial, because a weak bone cannot make the body function well.
It’s has cell wall to keep it safe
Breaking the body into systems is in most cases a lot easier for the students to understand instead of just doing it all at once
