Answer:
Humoral.
Explanation:
Hormones are the chemical messenger of the body that regulates the proper information to the target cell. Hormones are produced in the body by change in the external or internal environment.
The humoral stimulus mainly denotes the hormone regulation in response to the change in the blood concentration or ion concentration. The change in the calcium level of the body triggers the parathyroid gland to release parathyroid hormone and maintains the calcium level.
Thus, the answer is humoral stimulus.
