Final answer:
The Loop of Henle, located in the renal medulla, consists of a descending limb and an ascending limb. It is involved in the secretion and reabsorption of filtrate and plays a critical role in establishing an osmotic gradient for urine concentration.
Step-by-step explanation:
The correct answer is c) Loop of Henle. The Loop of Henle is a part of the nephron that is mostly located in the renal medulla. It consists of a descending limb and an ascending limb. The loop of Henle plays a critical role in the secretion and reabsorption of filtrate, as well as the regulation of water permeability. Its structure and function create a countercurrent multiplier system, establishing an osmotic gradient in the renal medulla that enables the concentration of urine.