Which event is considered the immediate cause of World War I?

What incident precipitated the start of World War I? Which event was the catalyst for the outbreak of World War I? What was the direct reason behind the outbreak of World War I? Which assassination is commonly seen as the catalyst for the outbreak of World War I? Which political figure's murder sparked the outbreak of World War I? Which significant political murder in 1914 sparked the First World War?Which incident on June 28, 1914, started the series of events that led to World War I? Which significant European event in 1914 sparked the start of World War I? Which historical occurrence is most frequently credited with starting World War I?