The correct answer to this open question is the following.
Unfortunately, you forgot to attach the map. Without the map, we do not know what the content is.
However, trying to help you, we find the map and can answer the following.
The area that is circled is called the Balkan Peninsula.
The Ottoman Empire is located at letter D.
Austria-Hungary is located south of Germany and west of Russia.
We are talking about one of the most conflictive zones previous World War I. Nationalistic and expansionistic ideas played a major role in the causes of conflicts.
However, one of the major causes of World War I was the assassination of Austrian-Hungary Archduke Franz Ferdinand and his wife on June 28, 1914. He and his wife Sophie were in Sarajevo to oversee the Austrian troops stationed there. During the war, the Allied Powers of France, Great Britain, Russia, Italy, and the US defeated the Central Powers comprised of Germany, Bulgaria, the Austria-Hungary Empire, and the Ottoman Empire.