Diabetes insipidus occurs due to the hyposecretion of
(a)Thymosin
(b)Oxytocin
(c)Insulin
(d)Vasopressin

Hint: Diabetes insipidus occurs due to the hyposecretion of a hormone which results in an imbalance of liquids in the body and overproduction of urine. Frequent urination is a symptom of Diabetes mellitus and thus this disease is also known as diabetes.

Complete step by step answer:
Diabetes insipidus occurs due to the hyposecretion of the hormone vasopressin which is synthesized by the hypothalamus and secreted by the posterior pituitary gland. Hypothalamus produces two hormones known as oxytocin and vasopressin which are transferred axonally to the posterior pituitary. Vasopressin is responsible for acting on the distal tubules of the nephron and increasing reabsorption of water and electrolytes. Since it prevents the formation of urine (diuresis), this hormone is also known as the antidiuretic hormone. When there is hyposecretion of vasopressin, there is excessive production of urine due to minimum absorption.

So, the correct option is ‘Vasopressin’.

Additional information: Let us look at the pituitary gland in detail.
-The pituitary gland is known as the master gland because its hormones control all endocrine glands but the hypothalamus controls the pituitary gland hence hypothalamus is known as the master of the master gland.
-The pituitary gland is attached to the hypothalamus by a stalk and is located inside a cavity of the skull known as the sella turcica.
-It is divided anatomically into adenohypophysis (anterior pituitary) and neurohypophysis (posterior pituitary).
-The anterior pituitary further consists of pars distalis and pars intermedia and the posterior pituitary consists of pars nervosa.
-The hormones secreted by the pars distalis region of the pituitary consists of growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Only one hormone is secreted by pars intermedia called melanocyte-stimulating hormone (MSH).

Note:
-Hypothalamus controls the anterior pituitary by secreting, releasing, and inhibiting hormones that stimulate or stop the secretion of pituitary hormones.
-These hypothalamic hormones reach the pituitary through a portal blood system.
-The posterior pituitary is however under the direct neural control of the hypothalamus.