105. A 45-year-old male stomach cancer patient underwent tumor removal surgery. After surgery, he developed megaloblastic anemia. His anemia is caused by a deficiency of X and can be treated with Y. (A)X = intrinsic factor； Y = folic acid. (B)X = intrinsic factor； Y = vitamin B12 (C)X = extrinsic factor； Y = parenteral iron (D)X = extrinsic factor； Y = sargramostim