I want to know the answer to the following question:
How many inventors came up with electric lamps before Thomas Edison?
All the background I'm provided with is that "They conclude that Edison's version was able to outstrip the others because of a combination of three factors: an effective incandescent material, a higher vacuum than others were able to achieve (by use of the Sprengel pump) and a high resistance that made power distribution from a centralized source economically viable.". Is that enough to answer the question?
Answer: no