<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 39-year-old woman presents to the clinic with complaints of constipation for the past 2 weeks. She reports that it has been getting increasingly difficult to pass stool to the point that she would go for 2-3 days without going to the bathroom. Prior to this, she passed stool every day without difficulty. She denies weight changes, headaches, chest pain, or abdominal pain but endorses fatigue. Her past medical history is significant for 2 episodes of kidney stones within the past 3 months. A physical examination is unremarkable. Laboratory studies are done and the results are shown below:Serum:Na: 138 mEqLCl-: 97 mEqLK: 3.9 mEqLHCO3-: 24 mEqL BUN: 10 mgdLGlucose: 103 mgdLCreatinine: 1.1 mgdLThyroid-stimulating hormone: 3.1 uUmLCa2: 12.1 mgdLPhosphate: 1.2 mgdL Normal: 2.5-4.5 mgdLWhat is the most likely explanation for this patients low phosphate levels?? A: Chronic renal disease caused by recurrent renal stones, B: Defective G-coupled calcium-sensing receptors in multiple tissues, C: Hereditary malfunction of phosphate absorption at the small brush border, D: Increase in calcium-sodium cotransporter activity at the distal convoluted tubule DCT, E: Inhibition of sodium-phosphate cotransporter at the proximal convoluted tubule PCT,  <response>: This is a clinical case about a 39-year-old woman with constipation and low serum phosphate levels. The key findings are:- Constipation for 2 weeks, getting progressively worse - History of 2 episodes of kidney stones in past 3 months- Normal physical exam except for constipation- Normal serum sodium, chloride, potassium, bicarbonate, BUN, glucose, creatinine, TSH, and calcium- Low serum phosphate levelThe question asks about the most likely cause of her low phosphate levels. Based on the history of recurrent kidney stones and normal renal function tests, chronic kidney disease is unlikely. There is no evidence to suggest defective calcium receptors or issues with intestinal absorption. The low phosphate with normal calcium suggests an issue with renal handling of phosphate. Specifically, increased activity of the sodium-calcium cotransporter in the DCT would increase calcium reabsorption, while inhibition of the sodium-phosphate cotransporter in the PCT would reduce phosphate reabsorption. Therefore, the most likely explanation is inhibition of the sodium-phosphate cotransporter in the PCT.E: Inhibition of sodium-phosphate cotransporter at the proximal convoluted tubule PCT 