Energy, work and power — practice question

The table gives the work done and the time spent by four machines. Which machine is the most powerful?

• Awork done $= 100\ \text{kJ}$, time taken $= 10\ \text{s}$
• Bwork done $= 100\ \text{kJ}$, time taken $= 20\ \text{s}$
• Cwork done $= 200\ \text{kJ}$, time taken $= 10\ \text{s}$
• Dwork done $= 200\ \text{kJ}$, time taken $= 20\ \text{s}$