If calcium is deficient in an expectant mother's diet, it is taken from which part of her body?

The correct choice identifies that if a pregnant woman has a deficiency of calcium in her diet, the body can compensate by drawing calcium from the large bones. This process reflects the body’s dynamic ability to maintain essential mineral levels during periods of increased demand, such as pregnancy.

During pregnancy, the demand for calcium increases significantly to support the developing fetus, especially for bone growth. The body prioritizes the fetal needs, utilizing the reserves stored in the mother's bones. Large bones act as a reservoir for calcium, which can be mobilized and released into circulation to maintain sufficient levels needed for both the mother and her developing child.

While calcium is also found in teeth and blood, the bones serve as the primary storage site from which calcium can be extracted when dietary intake is insufficient. This reserve helps ensure that both the mother's health and the nutritional requirements of the fetus are met. Muscles do not serve as a significant storage site for calcium in the same way that bones do, so they are not involved in addressing dietary deficiencies of calcium during pregnancy.