Final answer:
The countries that were initially on the side of the Central Powers at the start of World War I were Austria-Hungary, Germany, and the Ottoman Empire. Great Britain and Russia were part of the opposing Triple Entente, while Italy started out neutral before joining the Triple Entente in 1915.
Step-by-step explanation:
At the start of World War I, the countries that were on the side of the Central Powers were Germany, Austria-Hungary, and the Ottoman Empire. Great Britain and Russia were part of the Triple Entente and opposed the Central Powers. Italy, which had been allied with Germany and Austria-Hungary, initially declared neutrality and then joined the Triple Entente in 1915, opposing the Central Powers.
Ottoman Empire - Yes, joined the Central Powers in October 1914.
Great Britain - No, was a member of the Triple Entente.
Russia - No, was a member of the Triple Entente.
Austria-Hungary - Yes, a founding member of the Central Powers.
Italy - No, initially neutral, joined the Triple Entente (Allied Powers) in 1915.