Answer: A
Explanation: I did the test
All 3 of them explain the reason why people wear the mask to stop HIV
The renal medulla is made for the most part out of gathering channels and the nephron circles. You won't perceive any glomeruli in the medulla, as they are restricted to the cortex. This makes the renal cortex and renal medulla effortlessly recognizable.
Well so only good stuff goes in and only bad stuff comes out.