The correct answer to this open question is the following.
Although you forgot to attach the options for this question we can say the following.
In 1914 World War One erupted in a mountain range called the Balkans, located in southeastern Europe.
Yes, this is correct. The region where World War I started was the Balkans. Let's have in mind that Archduke Franz Ferdinand supported Austria-Hungary’s growth and dominance in the Balkans region.
Franz Ferdinand made possible the growth of the Austria-Hungary empire to dominate the region of the Balkans. However, on June 28, 1914, during a visit to Bosnia, he and his wife were assassinated by a Serbian nationalist. For this reason, Austria-Hungary declared the war on Serbia. In the next days, Germany declared war on Russia, invaded France, and this provoked Great Britain which declared war on Germany.
These events represented the beginning of World War I.