Respuesta :
Russia prepared to send troops to support Serbia when the Austria-Hungary declared war on the Slavic nation of Serbia.
Even though the Russia government had no treaty obligation to Serbia, they deployed troop with an aim to control the Balkans and because of long-term aim of gaining a military advantage over Germany and Austria-Hungary.
Hence, they prepared to send troops to support Serbia when the Austria-Hungary declared war on the Slavic nation of Serbia.
Therefore, the Option C is correct.
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