A person's bones will become brittle if he or she is deficient in:

• A. sodium.
• B. calcium.
• C. potassium.
• D. magnesium.

Answer: (B)

A deficiency in calcium is directly related to the health and strength of bones. Calcium is a crucial mineral that plays a vital role in bone formation and maintenance. The bones store about 99% of the body's calcium, and it is essential for bone density and strength. When there is insufficient calcium in the diet, the body may begin to leach calcium from the bones to maintain normal blood calcium levels. This process can lead to a condition known as osteopenia and, eventually, osteoporosis, which cause the bones to become brittle and more susceptible to fractures.

While sodium, potassium, and magnesium are essential for various bodily functions, they do not directly contribute to bone strength in the same way calcium does. Sodium is mainly involved in fluid balance, potassium is important for muscle function and regulation of fluids, and magnesium plays a role in numerous biochemical reactions, including the conversion of vitamin D into its active form, which is necessary for calcium absorption. However, none of these minerals are as critical as calcium when it comes to directly influencing bone density and strength.