Why is vasopressin given IM after a hypophysectomy?

To replace antidiuretic hormone (ADH) normally secreted by the pituitary.

After hypophysectomy or removal of the pituitary gland. the body cant synthesize ADH.Option A: Somatropin or growth hormone. not Vasopressin is used to treat growth failure.Option B: SIADH results from excessive ADH secretion.Option C: Mannitol or corticosteroids are used to decrease cerebral edema.