Here's a problem to solve: Every night, Johnny reads next to a lamp that is lit by an incandescent light bulb. Which is the best indication that the transfer of electrical energy to the lamp is inefficient?

Among the 4 following options, which is the correct answer?

- A: The bulb gets hot.
 
- B: The bulb produces light.
 
- C: The lamp uses copper wires.
 
- D: The lamp can be turned off at a switch.
 