Which of the Following Characterizes Normal Kidney Function

Which of the following characterizes normal kidney function?

A) filtration in which small molecules are lost, but large molecules are retained
B) reabsorption of small molecules, which are not waste products, from the urine
C) filtration in which small molecules are lost, but large molecules are retained and reabsorption of small molecules, which are not waste products, from the urine
D) none of these