What is the importance of the Maastricht Treaty in European history?

Correct answer: Important step toward formation of the European Union

The direct answer is A, an important step toward the formation of the European Union. The Maastricht Treaty was signed in 1992 and came into force in 1993. It created the European Union framework, strengthened cooperation among European countries and laid foundations for economic and monetary union, including the later euro. Option A is correct because the treaty gave European integration a new political and institutional form. Option B, the beginning of the Russian Revolution, belongs to Russian history in 1917. Option C, the colonial partition of Africa, is mainly associated with nineteenth-century imperial competition, not Maastricht. Option D, the end of the American Civil War, occurred in 1865. The accurate memory link is Maastricht = European Union, especially the 1990s.