Which of the following statements is true regarding the function of the renal tubule? 

• A

  Descending limb of the loop of Henle is nearly impermeable to water

• B

  Conditional reabsorption of ${\mathrm{Na}}^{+}$ and water occurs in the PCT

• C

  The maximum percentage of water is reabsorbed in the loop of Henle

• D

  Ascending limb of the loop of Henle is impermeable to water