A cyclist goes on a journey that lasts $250\,\text{s}$. The graph illustrates how the distance from the starting point changes with time. What is his average speed for the whole journey?
- A$1.0\,\text{m s}^{-1}$
- B$1.2\,\text{m s}^{-1}$
- C$1.5\,\text{m s}^{-1}$
- D$2.0\,\text{m s}^{-1}$