If the Urea Concentration in the Interstitial Fluid Around the Collecting

If the urea concentration in the interstitial fluid around the collecting duct is increased, urea reabsorption will

A) continue because it depends on active transport.
B) continue because it depends on passive transport.
C) cease because it depends on active transport.
D) cease, because reabsorption depends on passive transport. Instead, urea secretion will occur.