The correct explanation is: Incandescent bulbs produce other forms of energy, too, including heat.
Incandescent bulbs convert a significant portion of electrical energy into heat, which is why they are less efficient at producing light compared to compact fluorescent bulbs (CFLs). CFLs are designed to use the electrical energy more effectively to produce light while generating less heat, hence they can produce the same amount of light as an incandescent bulb while using less energy.