In the 1800s, the United States was still a very young nation, trying to solidify its identity. The Industrial Revolution began in Great Britain, a fast development of society following the introduction of machines. The United States was slower than Great Britain to fully embrace the changes. Yet key technological developments caused a rapid growth in American urban areas.

Which sentence serves as the authors thesis

Question

In the 1800s, the United States was still a very young nation, trying to solidify its identity. The Industrial Revolution began in Great Britain, a fast development of society following the introduction of machines. The United States was slower than Great Britain to fully embrace the changes. Yet key technological developments caused a rapid growth in American urban areas. 

Which sentence serves as the authors thesis