I think the first one is the correct answer
The term "Roaring '20s" refers to the decade of the 1920s in the United States, which was a time of much economic growth, as well as much social and cultural change.
In the 1920s, cities grew rapidly and industry was growing immensely in the United States. Jazz and other forms of entertainiment (like radio) were expanding and reaching new audiences. Women were becoming more involved in public life. The stock market was a place of much speculation and investment -- too much, as it turned out. The stock market crashed in 1929. America had thought it was in great times during the Roaring '20s. But then everything came crashing down and minds and hearts were depressed, as the country entered into the next decade and an economic tragedy known as the Great Depression.
It was the Mayans who built an ancient civilization, in what is now Mexico and Central America. They had an incredibly advanced civilization but were overcome by European settlers.
When the Monroe Doctrine was written, the US had just formed and was not ready to fight the European powers. Monroe basically asked Europe to stay out of the Western Hemisphere because they were afraid of getting attacked.
The creator, James Monroe, was interested in keeping the United States out of a war it was not prepared for. Though it was out of fear, there was some thinking through; people voted on it, after all.
Note that by "afraid of getting attacked," I not only mean getting attacked through soldiers and cannons but also by taking over nearby areas and competing with the US for natural resources.
The invention of the steam engine impacted industry in a variety of ways, not the least of which involved the European exploration and colonization of the African continent. Transportation, in general, was improved, proving profitable to businesses which could now transport products easier and faster. Another change of importance involves the location needed for factories, which no longer needed close proximity to rivers for energy.
