Question

what hormone is secreted by parafollicular cells?
calcitriol
calcitonin
vitamin d3
parathyroid gland

Explanation:

Parafollicular cells, also known as C - cells in the thyroid gland, secrete calcitonin. Calcitonin helps regulate calcium levels in the blood by decreasing blood calcium levels. Calcitriol is the active form of vitamin D and is produced in the kidneys. Vitamin D3 can be synthesized in the skin or obtained from the diet and is converted to calcitriol. The parathyroid gland secretes parathyroid hormone, not a hormone secreted by parafollicular cells.

Answer:

B. Calcitonin