A cyclist completes a journey that lasts $25\text{ s}$. The diagram shows how the distance travelled from her starting point changes with time. What is her average speed for the entire journey?
- A$6.0\,\text{m s}^{-1}$
- B$7.5\,\text{m s}^{-1}$
- C$10.0\,\text{m s}^{-1}$
- D$11.0\,\text{m s}^{-1}$