The diagram illustrates the movement of ions across the cell surface membrane. Within the cell, the concentration of sodium ions ($\mathrm{Na^+}$) is low and the concentration of potassium ions ($\mathrm{K^+}$) is high. Outside the cell, the concentration of $\mathrm{K^+}$ is low and the concentration of $\mathrm{Na^+}$ is high. The carrier molecule is a pump that swaps $\mathrm{Na^+}$ for $\mathrm{K^+}$ ions. Which ion movements are shown by the arrows?
- Aactive transport of $\mathrm{K^+}$: 2; active transport of $\mathrm{Na^+}$: 3; diffusion of $\mathrm{Na^+}$: 1; diffusion of $\mathrm{K^+}$: 4
- Bactive transport of $\mathrm{K^+}$: 2; active transport of $\mathrm{Na^+}$: 3; diffusion of $\mathrm{Na^+}$: 4; diffusion of $\mathrm{K^+}$: 1
- Cactive transport of $\mathrm{K^+}$: 3; active transport of $\mathrm{Na^+}$: 2; diffusion of $\mathrm{Na^+}$: 1; diffusion of $\mathrm{K^+}$: 4
- Dactive transport of $\mathrm{K^+}$: 3; active transport of $\mathrm{Na^+}$: 2; diffusion of $\mathrm{Na^+}$: 4; diffusion of $\mathrm{K^+}$: 1