The correct answer is option 3 - New York. New York was the first city to attain the status of a megacity. A megacity is typically defined as a city with a population of over 10 million people. New York City`s population surpassed this threshold in the early 20th century, making it the first megacity in the world. It is important to note that while London, Paris, and Washington D.C. are all major cities, they did not reach megacity status as early as New York. It is also worth mentioning that megacities are characterized by their size, population density, and economic importance. They often face unique challenges such as infrastructure management, urban planning, and providing resources and services for their large populations.