Final answer:
The parathyroid glands, located on the posterior surface of the thyroid, release parathyroid hormone to increase blood calcium levels when necessary.
Step-by-step explanation:
Located on the posterior lateral surfaces of the thyroid, the parathyroid glands are small and pea-shaped. If they release parathyroid hormone (PTH), the calcium levels in the body will increase. Therefore, the correct answer is c) Parathyroid, Parathyroid hormone (PTH), Calcium.
The parathyroid glands are embedded in the posterior surface of the thyroid gland and are critical in regulating blood calcium levels. When blood calcium levels are low, the parathyroid glands secrete PTH, which acts to increase blood calcium by stimulating the release of calcium from bones, increasing calcium absorption in the intestines, and reducing calcium loss in urine. Conversely, high blood calcium levels inhibit the secretion of PTH.