**Core Concept**
Ileal resection, a surgical procedure involving the removal of a portion of the ileum (the final portion of the small intestine), can lead to various complications due to its significant role in nutrient absorption and bile salt circulation. The ileum is crucial for the absorption of vitamin B12, bile salts, and other essential nutrients.

**Why the Correct Answer is Right**
The ileum plays a vital role in the absorption of vitamin B12, which is essential for the production of red blood cells. Vitamin B12 deficiency can lead to megaloblastic anemia, a condition characterized by the production of abnormally large red blood cells. The ileum is also responsible for the recirculation of bile salts, which are essential for the emulsification and absorption of fats.

**Why Each Wrong Option is Incorrect**
* **Option A:** Diarrhea is a common complication of ileal resection due to the reduced absorption of bile salts and increased stool water content, making it a correct complication.
* **Option B:** Weight loss is a possible consequence of ileal resection due to malabsorption of essential nutrients, making it a correct complication.
* **Option C:** Osteomalacia is a condition characterized by softening of the bones, often due to vitamin D deficiency. Ileal resection can lead to malabsorption of vitamin D, making it a correct complication.

**Clinical Pearl / High-Yield Fact**
It is essential to note that patients undergoing ileal resection require lifelong supplementation with vitamin B12 and possibly vitamin D to prevent deficiencies.

**Correct Answer: None**