Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

From time immemorial, cities have been the central gathering places of human life, from where the great ideas and movements of the world have sprouted. In this country, the beginnings of our independence fomented with the Boston Tea Party, while Philadelphia served as the home of the Constitutional Convention. The seeds of economic and financial power were sowed on the streets of New York City. Around the world, the great thinkers of the Renaissance assembled in Florence, the impressionist painters flocked to Paris, and the industrial revolution sparked in Birmingham England.

Hundreds of years later, great ideas and innovations are still sprouting in cities – but this time accompanied by a growth in urbanized life over the last several decades never before seen. For the first time in history, more people are living in cities than rural areas. And, this way of living is only going to continue: by 2050, the urban share of global population is projected to surpass 66 percent (up from 30 percent in 1950). This trend to urbanization is even more dramatic beyond the borders of the United States. Take Nigeria's capital, Lagos, which had a population of approximately 7.2 million in 2000, and is expected to rise to 24 million by 2030. And, eight times more Nigerians live in cities today than in 1975. Moreover, the metro areas of Tokyo, New York and Mexico City were the only metro areas in 1975 with at least 10 million people. Today, that list would include 31 such megacities – with 10 more to join by 2030 – all of which are outside the United States.

Cities are undergoing what Brookings Institution author Bruce Katz terms the "metropolitan revolution." Financial capitals New York and London are transforming into major world tech hubs as new and innovative companies emerge within these cities. And, this shift is not exclusive to New York or London, as many cities are undergoing similar transformations driven by this global trend toward urbanization. This wave of urban growth stems, in large part, from the mass adoption of the internet and interconnected technologies. Interestingly, many sociologists predicted years ago that the advent of such interconnectivity would enable people to live and work anywhere. But the practical result has been the opposite.

Indeed, in this new 21st century economy, innovative workers seek one another to collaborate in building and developing new knowledge-based industries that are increasingly disrupting and dominating a rapidly evolving global economy. Bright, curious minds in the sciences and technology demand proximity in order to be more productive, more creative and further stimulated. This need for collaboration has propelled millennials to move to urban areas in droves. But once they get there, they desire new open physical environments – such as incubators and shared work places – to enhance their collaborative efforts. Beyond work, a growing single population – one that now outnumbers married people in the United States – seeks out other singles amid the myriad activities and diverse nightlife that only cities offer.

(Adapted from https://www.usnews.com/)

What topic does the passage mainly discuss?