A 28-year-old male presents with left-sided flank pain and hematuria. On examination, a left-sided varicocele is noted that does not decompress when the patient assumes the supine position. CT abdomen at the level of the kidneys is performed. The structure marked **B** in the diagram shows normal caliber vessels and ureter, but imaging raises suspicion for compression of one of its major components. Which of the following anatomical relationships at the renal hilum best explains the clinical presentation?