Motion — practice question

A car travels along a road that is $20\,\text{km}$ long in $15$ minutes. What is the average speed of the car?

• A$0.75\,\text{km h}^{-1}$
• B$5.0\,\text{km h}^{-1}$
• C$80\,\text{km h}^{-1}$
• D$300\,\text{km h}^{-1}$