The correct answer to this question is The Black hand. This group had many alternative names including Union or Death and Crna Ruka.The Black hand formed in 1911 by Colonel Dragutin Dimitrijevic and were around until 1917. They were a secret society of Serbia. The group consisted of army officers and government offices and they promoted the liberation of Serbs by using terroristic methods.
Not only were they apart of the Franz Ferdinand assassination, they also helped the beginning of World War I. At the end of their existance, Dimitrijevic was executed and over 200 more were sent to prision.
The group named Black Hand conspired to assassinate Archduke Francis Ferdinand, and they were a secret military society which formed in 1901 by officers in the army of the Serbian Army. They were best known for their conspiracy to assassinate the Serbian royal couple in 1903.
The group was established to be actively pursuing the destruction of the ruling dynasty. Black Hand had a vast range of ideological outlooks. It was formed with the idea that all the territories with the South Slavic majority. Members of the group were mainly army officers with some government officials in the mix. It also operated in Belgrade, and it conducted campaigns and organized armed bands in Macedonia and established a network throughout Bosnia.