**Question:** Transport of glucose through apical membrane of enterocytes is -

A. Passive diffusion
B. Facilitated diffusion
C. Active transport
D. Osmosis

**Core Concept:** Glucose transport in enterocytes involves two main mechanisms: passive diffusion and facilitated diffusion. Passive diffusion is a passive transport process where glucose moves from an area of high concentration to an area of low concentration, driven by the concentration gradient. Facilitated diffusion, on the other hand, is an active transport process that helps glucose move across the cell membrane, using carrier proteins that bind to glucose molecules and transport them across the membrane.

**Why the Correct Answer is Right:** Among the given options, passive diffusion is not the correct answer as it does not involve the specific transport mechanism of glucose in enterocytes. Active transport, however, is not the correct answer, as it is not the primary mode of glucose transport in enterocytes. Instead, glucose primarily moves passively due to the concentration gradient, but it is facilitated by the presence of carrier proteins in facilitated diffusion.

**Why Each Wrong Option is Incorrect:**

A. Passive diffusion is an incorrect answer because it does not describe the specific transport mechanism used in enterocytes.
B. Osmosis is a process involving water movement across a semipermeable membrane in response to an osmotic difference, but it does not describe the glucose transport mechanism in enterocytes.
C. Active transport is the correct answer to the related question "What is the primary mode of glucose transport in enterocytes?", but not for the given question about the overall transport process.

**Clinical Pearl:** In the small intestine, glucose absorption is crucial for maintaining blood glucose levels and providing energy to other tissues in the body. This process involves both passive diffusion and facilitated diffusion, which together ensure efficient glucose absorption. Understanding these transport mechanisms is essential for understanding glucose homeostasis and the role of the small intestine in maintaining blood glucose levels.