FA 2019 P 573 - The only part of the nephron that first aid says has an effect on PO4 3- is PCT.

Early PCT—contains brush border. Reabsorbs all glucose and amino acids and most HCO 3 – , Na + , Cl – , PO 4 3– , K + , H 2 O, and uric acid. Isotonic absorption. Generates and secretes NH 3 , which enables the kidney to secrete more H + . PTH—inhibits Na + /PO 4 3– cotransport = Increased PO 4 3– excretion

PTH acts on the PCT to dec Phosphate reabsorption--> more Phosphate in the urine. PTH also acts at DCT to inc Ca reabsorption. This question was focused on the Phosphate aspect of the site of action for PTH.