A sprinter completes a $100\,\text{m}$ race in a straight line. Starting from the blocks, he increases his speed with a constant acceleration of $2.5\,\text{m s}^{-2}$ until he reaches a top speed of $10\,\text{m s}^{-1}$. He then continues at this speed until the finish line is crossed. How long does the sprinter take to complete the race?
- A$4\,\text{s}$
- B$10\,\text{s}$
- C$12\,\text{s}$
- D$20\,\text{s}$