Answer:
The correct answer is - parathyroid hormone.
Explanation:
Parathyroid hormone or parathormone is the hormone that secreted from the parathyroid gland located o the back of thyroid glands which regulates serum calcium level through its action on bone, kidney, and intestine.
Parathyroid hormone increase when there is a low concentration level of calcium ion (Ca2) in the plasma. When the calcium concentration is low in the blood PTH increase in blood and effect on bones, intestine and kidney to increase the calcium level in the blood.
