The diagram illustrates the energy transfer in a modern lamp. An electrical power input of $60\,\text{W}$ results in $12\,\text{W}$ of useful light power output and $48\,\text{W}$ of power wasted as heating the surroundings. Which expression represents the efficiency of the lamp?
- A$\frac{12}{60} \times 100\%$
- B$\frac{12}{48} \times 100\%$
- C$\frac{48}{60} \times 100\%$
- D$\frac{48}{12} \times 100\%$