Which war did the United States participate in during the 1900s?

The correct response highlights that the United States was involved in World War II during the 1900s, which occurred from 1939 to 1945. This global conflict saw the U.S. join the Allies, fighting against the Axis powers, including Germany, Italy, and Japan. America's participation in World War II was significant, leading to major military engagements and ultimately contributing to the victory of the Allies.

While the other options also represent wars in which the U.S. was involved—World War I (1914-1918), the Korean War (1950-1953), and the Gulf War (1990-1991)—it is important to identify that the question asks for a specific example of a conflict during the 1900s. Although multiple wars fall within this timeframe, recognizing World War II's prominent impact on both the U.S. and the global stage is essential. Understanding the significance of each conflict helps shed light on the evolving nature of U.S. involvement in international affairs throughout the 20th century.