Review Question - QID 211046

A 72-year-old man sees his primary care physician because he has been experiencing severe flank pain for the past 2 weeks. He says that the pain has an intermittent squeezing quality and radiates to the groin. Furthermore, the pain is associated with nausea and vomiting; however, he denies any abdominal pain. Physical exam reveals severe costovertebral angle tenderness, and urine dipstick reveals microscopic hematuria. Urinalysis reveals the findings demonstrated in Figure A. To prevent recurrence of these symptoms, he is given a drug to decrease excretion of a substance. Which of the following kidney segments is targeted by the drug that was most likely administered?