Review Question - QID 213785

A 71-year-old man presents to his cardiologist for ongoing management of his medications. He says that he has been taking all of his medications as directed and has had good control of his symptoms. His past medical history is significant for hypertension and congestive heart failure. He had an episode of decompensation after he ate a big meal during Thanksgiving. Physical exam reveals a heavy man with increased jugular venous distension and 2+ pitting edema to the knees bilaterally. He is also found to have rales in the lung bases and enlarged breast tissue bilaterally. The medication most likely responsible for his physical exam changes acts on which of the following regions of the kidney?