A 11-month old boy,weighing 3 kg,has polyuria,polydipsia and delayed motor milestones.Blood investigations show creatinine of 0.5 mg/dl,potassium 3 mEq/l,sodium 125 mEq/l,chloride 88 mEq/l,calcium 8.8 mg/dl,pH 7.46 and bicarbonate 26 mEq/l.Ultrasonography shows medullary nephrocalcinosis.The most likely diagnosis is:

• A. Renal tubular acidosis
• B. Diabetes insipidus
• C. Bartter's syndrome
• D. Pseudohypoaldosteronism