Which other member of the triple alliance first supported austria-hungary’s invasion of serbia? germany ottoman empire russia great britain

Answer;
Germany was the other member of the Tripple Alliance that first supported Austria-Hungary's invasion of Serbia.

Explanation; 
Triple Alliance was a secret agreement between Germany, Austria-Hungary, and Italy that was formed in 1882 and renewed periodically until the first world war. The Assassination of Archduke Franz Ferdinand of Austria, heir to the Austro-Hungarian throne, was killed in Sarajevo along with his wife by a Serbian nationalist, this made the Austria-Hungary to declare war on Serbia, effectively beginning the World War I. 

Russia very famously supported Serbia that's what lead to the Great War: it's a wrong answer. 

The Trippe Alliance was Austria-Hungary, Germany and Italy so the correct answer is: Germany.