The correct answer is D. no article.
The First World War was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. Contemporaneously described as "the war to end all wars", it led to the mobilisation of more than 70 million military personnel, including 60 million Europeans, making it one of the largest wars in history. Over 16 million people died, including 9.7 million Europeans, and an additional 7.9 million were wounded. Tens of millions of people died due to genocides (including the Armenian genocide, the Holocaust, and the Holodomor), premeditated death from starvation, massacres, and disease. Aircraft played a major role in the conflict, including in strategic bombing of population centers, the development of tanks, the use of chemical weapons, and the first use of submarines against merchant shipping.
The war began after the assassination of Archduke Franz Ferdinand of Austria, heir presumptive to the Austro-Hungarian throne, and his wife Sophie, by Gavrilo Princip, a Serbian nationalist on 28 June 1914. Serbia's allies, Russia and France, and Austria-Hungary's ally, Germany, were drawn into the conflict. Within weeks, the major powers were at war and the conflict had expanded into a global war. The Central Powers—Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria—became known as the "Central Powers", while the Entente Powers—Russia, France, the United Kingdom, Italy, Japan, and the United States—became known as the "Entente Powers".
The war ended with the signing of the Armistice of 11 November 1918. The Allies and the Central Powers signed the Treaty of Versailles in 1919. The war had a profound effect on the course of the 20th century. It led to the collapse of the Austro-Hungarian, Ottoman, and Russian Empires, and the creation of new countries, including Czechoslovakia, Yugoslavia, and Poland. The war also led to the formation of the League of Nations, an international organisation that was intended to prevent future wars.
