1. How have the U. S. government, groups, and individuals reacted to the issues and challenges of the 21st Century?

The correct answer to this open question is the following.

Although the question does not have any reference, context, or attachment, we can say that the U.S. government, groups, and individuals have reacted in different ways to the issues and challenges of the 21st Century.

The United States lives different issues such as the permanent terrorist threat from terrorist groups in the Middle East. After the September 11, 2001 attacks, the federal government acted promptly and created the Homeland Security Department and sent the US Force to air raid Afghanistan.

Another important issue is globalization and Free Trade. That is why the US, México, and Canada have reviewed and adopted the North American Free Trade Agreement (NAFTA) to modernize it to the new necessities and now have signed USMCA, the United States, México, and Canada Agreement. Some people support it, others think it is no good for American Unions. Many others consider is of great help not only for the US but for the other two countries too.  

can you explain it better