Answer:
The lightbulb was the most significant invention. Other inventions such as the airplane and telephone have substitutes, whereas the lightbulb has one which isn’t very good. Without the lightbulb, people would have to use fire or sunlight as light sources… or electricity in some other way. Sunlight would be the most natural source of light, thus it will be the easiest to use, but fire can be moved to different places and can be controlled. Due to this, it is likely that sunlight would be used during the day, and torches and candles will be used in the night. This means that cars will have to find a way to use torches/candles for headlights, and structures will have to be made out of non-flammable substances. In conclusion, the lightbulb is the most useful and significant invention.