Which nations comprised the Allied Powers during World War I?

The correct choice identifies the key nations that formed the core of the Allied Powers during World War I. Britain, France, and Russia were integral members of this coalition fighting against the Central Powers, which included Germany, Austria-Hungary, and the Ottoman Empire.

Britain and France, with longstanding military and colonial interests, formed a military alliance well before the war began, and Russia joined them due to shared concerns about German expansionism and a commitment to defend Serbia following the assassination of Archduke Franz Ferdinand. Together, these nations coordinated their military efforts and strategies throughout the war, contributing significantly to the eventual victory of the Allies in 1918.

The other options include nations that either were part of the Central Powers or had different roles during the war. For instance, Italy initially was part of the Triple Alliance with Germany and Austria-Hungary but switched sides to join the Allies in 1915. The Ottoman Empire was an ally of Germany and Austria-Hungary, while Serbia was initially aligned with the Allies but was not one of the major powers making up the core Allied coalition. Thus, option A accurately reflects the primary nations in the alliance that opposed the Central Powers.