Answer the question by choosing responses from the following:
1) Sodium: plays a crucial role in the reabsorption of H+ ions in the kidneys.
2) Potassium: Present outside the cell in 10 times higher concentration than inside.
3) Calcium: Its concentration in the blood is increased by parathyroid hormone (PTH).
4) Hydrogen ions: are secreted in the renal tubules to reabsorb K+ ions.
5) Phosphate: Parathyroid hormone (PTH) acts on the kidneys to decrease phosphate reabsorption, resulting in increased urinary excretion of phosphate.
6) Ammonium ions: helps in the formation of urea in the DCT.
Which of the above options correctly matches the ions with their description?
