The calcitonin hormone is produced by the _____.

Correct option is B

Calcitonin is produced by the parafollicular (C-cells) of the thyroid gland and helps regulate calcium levels in the blood. It lowers blood calcium by inhibiting osteoclast activity in bones and enhancing calcium excretion by the kidneys. It works opposite to parathyroid hormone, which raises blood calcium levels. Calcitonin plays a crucial role in calcium homeostasis, especially during periods of high demand.
Explanation of options: (a) ✘ Parathyroid gland – Produces parathyroid hormone (PTH), which increases calcium levels in the blood. (b) ✔ Thyroid gland – Its C-cells secrete calcitonin, which reduces blood calcium levels. (c) ✘ Adrenal medulla – Secretes catecholamines like adrenaline and noradrenaline, not involved in calcium metabolism. (d) ✘ Adrenal cortex – Produces steroid hormones like cortisol and aldosterone, unrelated to calcitonin.