Okay, let's tackle this question. The question is about which sugar is taken up by enterocytes via facilitated diffusion. The options aren't provided, so I'll need to think of common sugars and their absorption mechanisms.

First, I remember that glucose and galactose are absorbed via active transport, specifically through the SGLT1 transporter in the small intestine. This is a secondary active transport process, using the sodium gradient. Fructose, on the other hand, is absorbed differently. I think fructose uses facilitated diffusion via the GLUT5 transporter. That would mean fructose is the correct answer here.

Wait, but what about other sugars like lactose or sucrose? Those are disaccharides and need to be broken down first by enzymes like lactase or sucrase into monosaccharides before absorption. So they wouldn't be taken up directly. So the options might include glucose, fructose, galactose, or maybe something else. Since the correct answer is fructose, I need to make sure that the options include fructose and other sugars that use active transport.

The core concept here is the different mechanisms of monosaccharide absorption in the small intestine. Facilitated diffusion requires a transporter but no ATP, relying on concentration gradients. Active transport uses energy, usually from ATP or coupled with another ion's gradient.

So for the explanation, the core concept would be about the absorption mechanisms. The correct answer is fructose because it uses GLUT5, which is a facilitated diffusion process. The other options like glucose and galactose use active transport (SGLT1), and disaccharides like sucrose aren't directly absorbed. The clinical pearl would be to remember that fructose is the exception using facilitated diffusion instead of active transport. That's a high-yield fact for exams.

**Core Concept** The absorption of monosaccharides in the small intestine involves distinct transport mechanisms. Glucose and galactose use **Na⁺-dependent secondary active transport** (SGLT1), while **fructose** is absorbed via **facilitated diffusion** through **GLUT5 transporters**.

**Why the Correct Answer is Right** Fructose is the only monosaccharide absorbed by **facilitated diffusion** in enterocytes. Unlike glucose and galactose, which require energy-coupled SGLT1 transporters, fructose moves passively down its concentration gradient using **GLUT5**, a uniporter transporter. This mechanism does not depend on sodium gradients or ATP hydrolysis, distinguishing it from other sugars.

**Why Each Wrong Option is Incorrect**
**Option A:** Glucose is absorbed via **SGLT1-mediated active transport**, not facilitated diffusion.
**Option B:** Galactose, like glucose, uses **SGLT1** for active transport.
**Option D:** Disaccharides (e.g., sucrose, lactose) are first hydrolyzed by brush border enzymes (e.g., sucrase, lactase) into monosaccharides before absorption. They are not directly absorbed.

**Clinical Pearl / High-Yield Fact** Remember **"GAL-FRUC"**: **G**lucose, **A**lactose, and **L**actose use **active transport** (SGLT1), while **F**ructose uses **facilitated

✓ Correct Answer: C. Fructose