Co-transport of nutrients across the intestinal cell membranes is an active process that can move glucose against a concentration gradient. The energy requiring step for co-transport:

A.	The Na+K+ATPase that pumps Na+ from the cell into the lumen of the intestine.
B.	The permease that allows glucose and Na+ into the cell requires ATP.
C.	The permease that pumps glucose from the cell into the blood requires ATP.
D.	The Na+K+ ATPase that pumps Na+ from the cell into the blood, maintaining low Na+ levels in the cell. The Na+K+ ATPase moves Na+ out of the epithelial cells lining the intestine and into the blood. The reduced concentration of Na+ inside the cell coupled with high Na+ inside the lumen of the intestine provides a driving force for the movement of Na+ into the cell. The cotransporters in the membrane of the epithelial cell facing the intestine allow Na+ to enter only when accompanied by either glucose or one of the amino acids (each have their own set of co-transporters). Glucose then moves into the blood through a permease in the membrane between the cell and the blood. Thus, ATP is used as an energy source to drive Na+ out of the cell resulting in glucose transport from the intestine to our blood.