(A) Support France against Germany
(B) ** Support Serbia against Austria-Hungary
(C) Protect itself against the British navy
(D) Support Austria-Hungary against Bosnia-Herzegovina
EXPLANATIONS BELOW
Concept note-1: -The Russian Empire gradually entered World War I during the three days prior to 28th July 1914. This began with Austria-Hungary’s declaration of war against Serbia, which was a Russian ally. The Russian Empire sent an ultimatum, via Saint Petersburg, to Vienna, warning Austria-Hungary not to attack Serbia.
Concept note-2: -Russia. Following the declaration of war on Germany, Russian Emperor Nicolas II issued a manifesto announcing that in response to the Austro-Hungarian declaration of war against the Russian Empire, Russia would enter into war against Austria-Hungary. This occurred on on July 26, 1914.
Concept note-3: -Austria-Hungary, with German encouragement, declared war on Serbia on 28 July. Russia’s support of Serbia brought France into the conflict.
Concept note-4: -The declaration of war was made after Serbia rejected the terms in an ultimatum sent to them by Austria on July 23, after Archduke Franz Ferdinand, heir to the Austria-Hungary throne, had been assassinated by Serbian student, Gavrilo Princip, in Sarajevo.
Concept note-5: -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.