Anti-diuretic hormone is secreted at the time of:

Explanation

The anti-diuretic hormone (ADH), also known as vasopressin, is secreted by the posterior pituitary gland. It plays a crucial role in maintaining water balance within the body by promoting water reabsorption in the kidneys. During dehydration, the body needs to conserve water, and therefore, ADH is secreted to reduce water loss through urine. In contrast, conditions like constipation, micturition, and hypertension do not directly stimulate the secretion of ADH. Constipation involves the digestive system, micturition refers to the act of urination, and hypertension is related to blood pressure regulation.