Calcium Is Very Important to the Normal Functioning of the Body

Multiple Choice

Calcium is very important to the normal functioning of the body, so it is very important that the plasma Ca²⁺ concentration be well regulated. In which of the following ways does calcium play an important role?

A) calcium plays an important role in the absorption of Vitamin D from the digestive tract.
B) calcium is important for maintaining the proper excitability of nerves and muscles.
C) calcium stimulates osteoblasts to lay down bone.
D) both (a) and (b) above.
E) all of these answers.