If a sodium-potassium pump operates 100 times, how many sodium ions are moved out of the cell and how many potassium ions are moved into the cell?

• A. 300 sodium ions out, 200 potassium ions in
• B. 300 sodium ions in, 200 potassium ions out
• C. 200 sodium ions out, 300 potassium ions in
• D. 200 sodium ions in, 300 potassium ions out

Answer: (A)