This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidneys and Body Fluids, Subject name: Physiology
Which cells in the kidney produce 1,25 dihydroxy - cholecalciferol? 
Select and explain. 
A. Granular cells, B. Proximal convoluted tubule cells, C. Mesangial cells, D. Peritubular cells
B: Proximal convoluted tubule cells
Answer: B: Proximal convoluted tubule cells 
Explanation: Ans. B Proximal convoluted tubular cellsRef: Contemporary Nephrology, 1st ed. pg. 164 and Indu KhuranaGranular cellsProduce reninProximal convoluted cellsContain 1 alpha hydroxylase that is essential to produce vitamin D3 Mesangial cellsRegulate RBC leakagePeritubular cellsProduce erythropoietin