Before his presidency, Dwight D. Eisenhower served as a general in which conflict?

Dwight D. Eisenhower served as a general during World War II, which is the correct answer. His prominent role in the war included serving as the Supreme Commander of the Allied Expeditionary Forces in Europe, where he was responsible for planning and executing major operations such as the D-Day invasion of Normandy in 1944. Eisenhower's leadership during this critical conflict significantly shaped his public persona and political career, ultimately paving the way for his election as President of the United States in 1952.

The other choices pertain to conflicts in which Eisenhower either did not serve or had a different role. He was not involved in World War I, which took place before his military career began. While he did not serve in combat during the Korean War, he became involved in that conflict as president, but his military fame primarily came from World War II. The Vietnam War occurred later, after he had already left office and would not have been a conflict he served in directly.