A 10-month-old boy,weighing 3 kg has polyuria,polydipsia and delayed motor milestones.Investigations show blood levels of creatinine 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 syndrome
• D. Pseudohypoaldosteronism