Which is following statement is true ?

• A. Descending limb of loop of Henle is permeable to solutes
• B. Fluid coming from the descending limb of loop of Henle is hypotonic
• C. Clearance of substance is always more than GFR if there is tubular secretion
• D. If clearance of a substance is greater than GFR , then tubular secretion must be present