**Core Concept:** The small intestine is divided into two parts: the ileum and the jejunum. The ileum is the final part of the small intestine, while the jejunum is the middle part. Both are involved in the absorption of essential nutrients.

**Why the Correct Answer is Right:** If 90% of the ileum and jejunum are resected, the overall absorption of nutrients in the remaining part of the small intestine will be compromised significantly. This will lead to malabsorption syndromes, such as fat malabsorption and protein malabsorption, due to the loss of the specific enzymes and receptors present in these segments for the absorption of fats (lipase, bile salts, and phospholipase A2 in the ileum), and proteins (peptidases in the jejunum).

**Why Each Wrong Option is Incorrect:**

A. Malabsorption is unlikely to occur with 10% resection, as the remaining tissue would be sufficient to maintain essential nutrient absorption.

B. Resection of 90% of the ileum and jejunum would lead to fat malabsorption due to the loss of lipase, bile salts, and phospholipase A2, which are crucial for fat digestion and absorption.

C. Protein malabsorption is more likely to occur with 90% resection, as the majority of the jejunum has been removed, resulting in a decrease in protein absorption (peptidases in the jejunum).

D. This option is incorrect as the malabsorption syndromes would still occur due to the loss of enzymes and receptors in the resected segments.

**Clinical Pearl:** In cases of extensive small bowel resection, it is essential to consider the potential development of malabsorption syndromes, including fat and protein malabsorption, which can lead to nutritional deficiencies and clinical consequences. Adequate preoperative assessment and planning are crucial to minimize the extent of resection and preserve nutrient absorption.