**Core Concept**
The massive resection of small bowel, also known as short bowel syndrome, is a condition where a significant portion of the small intestine is removed, leading to malabsorption of nutrients. This condition highlights the importance of the small intestine's role in nutrient absorption and its adaptation mechanisms.

**Why the Correct Answer is Right**
The correct answer is related to the adaptations that occur in the small intestine after a massive resection. One of the key adaptations is the increased absorption of bile salts from the distal small intestine and colon, which is mediated by the enzyme bile salt-binding protein. This adaptation helps to conserve bile salts, which are essential for fat digestion and absorption.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the massive resection of small bowel typically leads to malabsorption of nutrients, including carbohydrates, proteins, and fats, rather than an increase in absorption.
* **Option B:** This option is incorrect because the resection of small bowel does not lead to an increase in the absorption of vitamin B12, which is primarily absorbed in the terminal ileum.
* **Option C:** This option is incorrect because the massive resection of small bowel does not lead to an increase in the absorption of bile salts, which is actually conserved through the adaptation of bile salt-binding protein.

**Clinical Pearl / High-Yield Fact**
One of the key clinical features of short bowel syndrome is the development of steatorrhea (fatty stools) due to malabsorption of fats and bile salts. This condition requires aggressive nutritional support and management to prevent malnutrition and complications.

**Correct Answer: B. Massive resection of small bowel typically leads to malabsorption of nutrients, including proteins.**