The correct option is B Vitamin D
The parathyroid glands secrete a peptide hormone called parathyroid hormone (PTH). The secretion of PTH is regulated by the circulating levels of calcium ions.
PTH is a hypercalcemic hormone. It increases calcium absorption in small intestine by regulating metabolism of vitamin D by stimulating osteoclasts. These are the cells that cause breakdown by dissolution of calcium from bone and thus, concentration of calcium is increased in blood. Therefore, PTH increases Ca2+ levels in the blood, absorption in the bone and increases its absorption in digested food.