The correct response is:
Fluorescent bulbs produce other forms of energy, too, including heat.
Compact fluorescent bulbs (CFLs) are more energy-efficient than incandescent bulbs because they convert a larger portion of electrical energy into visible light rather than heat. Incandescent bulbs waste a significant amount of energy as heat, which is why they are less efficient. Thus, CFLs can provide the same amount of light (lumens) while using less electrical energy (watts).