Final answer:
Calcium and Vitamin D are necessary for optimal bone growth as calcium is a critical component of bone, and vitamin D is needed for calcium absorption. The correct option is (C).
Step-by-step explanation:
Calcium and Vitamin D
You already know that calcium is a critical component of bone, especially in the form of calcium phosphate and calcium carbonate. Since the body cannot make calcium, it must be obtained from the diet.
However, calcium cannot be absorbed from the small intestine without vitamin D. Therefore, intake of vitamin D is also critical to bone health.
In addition to vitamin D's role in calcium absorption, it also plays a role, though not as clearly understood, in bone remodeling.