An electrician is raised by a lifting machine, as illustrated. The lifting machine needs $4.5\,\text{s}$ to move the electrician upward through a vertical distance of $3.2\,\text{m}$. The electrician has a mass of $72\,\text{kg}$. The energy for the lifting machine comes from a $2.0\,\text{kW}$ electric motor. What is the efficiency of the lifting machine?
- A$0.026$
- B$0.25$
- C$0.50$
- D$0.75$