The correct option is C Addison's disease
Addisons disease is a chronic endocrine system disorder in which the adrenal glands do not produce sufficient steroid hormones (glucocorticoids and often mineralocorticoids). The commonest cause of hyponatraemia in clinical practice is dilutional hyponatraemia due to retention of water in excess of sodium. This requires a deficit in renal water excretion which is usually due to, or accompanied by, an inability to adequately suppress antidiuretic hormone.