One way of balancing the concentration of ions and molecules within a cell to maintain homeostasis is to use all but ______________ . ATP transfers one of its phosphate groups (becoming ADP) to a transfer protein. This protein changes its conformation so it can bring needed ions into the cell and get rid of unnecessary ions.

Responses
A cellular energycellular energy
B active transportactive transport
C membrane proteinsmembrane proteins
D phospholipid channels