Final answer:
C) pyramids.
The triangular-shaped divisions of the medulla of the kidney are the renal pyramids, which contain collecting ducts and loops of Henle, and are separated by renal columns in the kidney's structure.
Step-by-step explanation:
The triangular-shaped divisions of the medulla of the kidney are the renal pyramids. These cone-shaped tissues are critical components of the kidney's internal structure and contain important elements like collecting ducts and the loops of Henle associated with juxtamedullary nephrons. The renal pyramids are located in the renal medulla and are numbered six to eight in each kidney. They are separated from each other by extensions of the renal cortex known as renal columns. Urine is collected by the papillae at the tips of the pyramids and drained into the minor calyces, which then leads to the major calyces forming the renal pelvis, and eventually drains into the ureter.