A boy completes $400\ \text{m}$ at an average speed of $4.0\ \text{m s}^{-1}$. He covers the first $200\ \text{m}$ in $40\ \text{s}$. How much time does he need to cover the second $200\ \text{m}$?
- A$60\ \text{s}$
- B$66.7\ \text{s}$
- C$80\ \text{s}$
- D$140\ \text{s}$