A 1 month old baby presents with frequent vomiting and failure to thrive.There are features of moderate dehydration.Blood sodium is 122 mEq/1 and potassium is 6.1 mEq/1.The most likely diagnosis is:

• A. Bartter syndrome
• B. Gitelman syndrome
• C. 11-beta hydroxylase deficiency
• D. 21-hydroxylase deficiency