单选题 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 cotransport is(    )．
   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