The table below shows the concentration of oxygen in arbitrary units (a.u.\text{a.u.}a.u.) outside and inside four different respiratory cells, A, B, C, and D.
| Cell | Oxygen concentration outside (a.u.\text{a.u.}a.u.) | Oxygen concentration inside (a.u.\text{a.u.}a.u.) |
|---|---|---|
| A | 14 | 11 |
| B | 18 | 10 |
| C | 15 | 14 |
| D | 9 | 13 |
Based on the table, answer the following questions:
Which cell has the smallest difference in oxygen concentration between the outside and the inside of the cell?
Into which cell will oxygen diffuse into the fastest?