Answer:
In both cases, the sound and spelling are the same, and only the definition changes. Here are 30 more examples of homonyms. Note that some homonyms have more than two meanings (for example, "tender" can also mean sensitive, easily chewed, or even refer to chicken strips), but to keep things simple we've only included two in our homonyms list:
The correct option is SKELETAL SYSTEM.
Calcium is a mineral that is found in many food and the body needs it to maintain strong bones and teeth and to carry out some biochemical reactions in the body. Calcium in the body is stored in bones and teeth; calcium supports the structure and hardness of these body parts.