The nervous system and endocrine system play important roles in helping the body maintain homeostasis. The nervous system processes input when something is out of its optimal range. The nervous system can then determine the best course of action to correct the imbalance. Sometimes the nervous system stimulate the glands of the endocrine system to release hormones and other times, it can cause a response such as shivering or sweating to help return the body to its steady state. Calcium is a crucial nutrient used in many bodily processes from muscle contraction to blood clotting. The nervous and endocrine system work hand in hand to control calcium levels throughout the body.
Using the diagram, what action is taken when calcium levels are too high?

A) The thyroid glands release PTH.
B) The parathyroid glands release PTH.
C) The thyroid gland releases calcitonin.
D) The parathyroid glands release calcitonin.