Motion — practice question

A train sets off from a station and covers $60\ \text{km}$ in $20\ \text{minutes}$. What is the train's average speed?

• A$3.0\ \text{m s}^{-1}$
• B$5.0\ \text{m s}^{-1}$
• C$50\ \text{m s}^{-1}$
• D$60\ \text{m s}^{-1}$