Answer:
Glucose entering the intestines from the villus.This is by active transport.The latter is defined as the movement of molecules and solutes from the region of lower concentration to the region of higher concentration against the concentration gradient.
Explanation:
All the above options depends on the diffusion gradients from one higher region to another.e.g oxygen passing from high concentration from outside to lower concentration in blood stream,like wise Co2 from higher concentration from inside to outside,with passive diffusion lipids and water enter the small intestine(note amino acid and glucose,and fructose are different).
Active transport( through sodium dependent transporter) transports glucose to the intestine from the villus.This is movements against concentration gradient because,glucose molecule are concentrated in intestine,and needed by the cells, in the body.Therefore they must be transported as a fast rate inn the blood .
However the absorption by the villi is very slow,therefore active transport is needed to move these against the concentration gradient into the intestine.And finally the blood.
If this were to be moved by passive diffusion,the high concentration in the intestine will force this back into the villi
Therefore extra energy is needed by active transport for the glucose molecules to enter the intestine from the villus.
