This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
In a patient if administration of exogeneus vasopressin does not increase the osmolality of urine the likely cause is 
Select and explain. 
A. SIADH, B. Psychogenic polydipsia, C. Renal Hyposensitivity to ADH, D. ADH Deficiency
C: Renal Hyposensitivity to ADH
Answer: C: Renal Hyposensitivity to ADH 
Explanation: Answer is C (Renal Hyposensitivity to ADH): Failure of urine osmolality to rise even after administration of exogenous ADH/vasopressin suggests a diagnosis of Nephrogenic Diabetes Insipidus due resistance to action of vasopressin on the Renal tubule (Renal Hyposensitivity to ADH).