<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 58-year-old woman with type 2 diabetes mellitus comes to the physician because of generalized pain and muscle weakness. She suffered a nondisplaced left ulnar fracture 3 months ago after lifting a heavy crate of books. She has had progressively worsening renal function over the past 2 years but has not yet started hemodialysis. An x-ray of the left wrist shows a healing fracture in the ulna with thinned cortices. There are multiple transverse radiolucent bands adjacent to the fracture, surrounded by a thin sclerotic margin. This patients findings are most likely due to the impaired production of which of the following substances?? A: 25-hydroxycholecalciferol, B: 1,25-dihydroxycholecalciferol, C: Ergosterol, D: Cholecalciferol, E: 7-dehydrocholesterol,  <response>: This is a question about impaired production of a substance leading to generalized pain, muscle weakness, and a fracture with radiographic findings of transverse radiolucent bands surrounded by sclerotic margins in a patient with chronic kidney disease. The radiographic findings are consistent with osteomalacia. Osteomalacia is caused by impaired mineralization of newly formed osteoid which leads to accumulation of unmineralized bone matrix. This is typically due to vitamin D deficiency, as vitamin D is required for intestinal absorption of calcium and phosphorus which are needed for bone mineralization. The choices list different forms of vitamin D. In chronic kidney disease, there is impaired production of the active form of vitamin D, 1,25-dihydroxycholecalciferol, due to reduced renal mass and loss of 1α-hydroxylase activity. This leads to reduced calcium and phosphorus absorption and osteomalacia.B: 1,25-dihydroxycholecalciferol 