Final answer:
The chemical force for which both potassium and sodium ions are directed into the cell is due to the activity of the sodium-potassium pumps in the cell membranes.
D) both potassium and sodium
Step-by-step explanation:
In cells, the chemical force for which both potassium and sodium ions are directed into the cell is due to the activity of the sodium-potassium pumps in the cell membranes.
These pumps use ATP to pump sodium out of the cell and potassium into the cell, creating a higher concentration of potassium inside the cell and a net negative charge inside the cell. Thus, both potassium and sodium ions are directed into the cell.