Read the following excerpt from the article “Charles Steinmetz: Master of Electricity”: This young mathematician with a fascination for the new science of electricity had come to America at a perfect time. It was the dawn of the electric age. Just ten years earlier, Edison had invented the light bulb. Only a few streets in big cities were illuminated by Edison’s lights, but the drive was on to harness the power of electricity and expand its use. (paragraph 5)

Based on the context, what does the word illuminated most likely mean?

made useable
improved
lit
built