The correct answer would be: D
D. doesn't lead to a productive end.
No it is not the main energy source
<span>The nephron is the basic structural and functional unit of the kidney, it regulates the concentration of water and soluble substances like sodium through filtering the blood, reabsorbing what is needed and excreting the rest as urine. Therefore urine should be free of blood as the nephron filters the blood, cleaning it for the body to reuse.</span>
