(A) France
(B) U.S
(C) Great Britain
(D) ** Austria-Hungary
EXPLANATIONS BELOW
Concept note-1: -Austria-Hungary declares war on Serbia. Germany declares War on Russia.
Concept note-2: -On July 28, 1914, one month to the day after Archduke Franz Ferdinand of Austria and his wife were killed by a Serbian nationalist in Sarajevo, Austria-Hungary declares war on Serbia, effectively beginning the First World War.
Concept note-3: -Telegram of Austria-Hungary‘s declaration of war on Serbia on 28th July 1914 marked the beginning of the First World War – one of the world’s most tragic conflicts in the history of human race and initiated the era of unprecedented suffering.
Concept note-4: -The result would be the Great War that changed the course of the twentieth century. The immediate reason for Austria’s ultimatum was the assassination of Archduke Franz Ferdinand and his wife Sophie in Sarajevo, Bosnia on June 28, 1914 by the Bosnian Serb nationalist, Gavrilo Princip.