The choice that doesn't reflect a main process which allows nutrients to be absorbed from the GI tract into circulation is active diffusion among these possible answers. So your answer would be B - active difusion.
The main reason for this is that all of the other ones are implicated and play active roles in the process of nutrient absorption from the GI tract into circulation.
Answer is B i.e. active diffusion. Absorption is the process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph. It is carried out by passive, active or facilitated transport mechanisms.
Explanation:
Monosaccharides like glucose, amono acids and some electrolytes like chloride ions are absorbed by simple diffusion. It depends upon the concentration gradients.
Some other substances like fructose and some amino acids are absorbed with the help of carrier ions like Na+. This mechanism is called the facilitated diffusion.
Active transport occurs against the concentration gradient. Various amino acids, glucose, Na+ are absorbed into the blood by this mechanism.
