Which of the Following Do Calcium, Phosphorus, and Magnesium Have

Multiple Choice

Which of the following do calcium, phosphorus, and magnesium have in common?

A) They all exist in circulation as only free or ionized forms.
B) They all exist as free or ionized forms, bound to proteins and complexes to radicals, e.g., sulfates to form salts.
C) Calcium exists as bound and free only, phosphorus exists only as bound and complexes to radical to form salts and magnesium exists as free or ionized forms, bound to proteins and complexes to radicals to form salts.
D) Calcium blood levels are regulated by parathyroid hormones, phosphorus is regulated by testosterone, and magnesium is regulated by insulin.