Name one war fought in the 1900s.

World War I is indeed a significant war fought in the 1900s, primarily from 1914 to 1918. This global conflict involved many of the world's nations, including major powers divided into two opposing alliances: the Allies and the Central Powers. The war had far-reaching effects on the geopolitical landscape and led to significant changes in borders, the rise of new nations, and set the stage for subsequent conflicts, including World War II.

The other wars listed occurred in different centuries; for example, The Revolutionary War took place from 1775 to 1783, while the War of 1812 was fought between the United States and Great Britain from 1812 to 1815. The Spanish-American War occurred in 1898, just before the 20th century. Therefore, among the options provided, World War I is the only one that directly pertains to the timeline specified — the 1900s.