After the build up of anxiety from Nationalism, Imperialism and Militarism, the Powers were worried about being attacked by each other.To counter this alliances were formed. Germany made a mystery alliance with Austria-Hungary in 1879. The Alliance System was certainly a prominent reason of WWI.
The correct answer is B: Developing skilled-labor Industries.
Austria followed Switzerland's model by developing skilled-labor Industries. Austria as an extended market economy as well as a skilled labor force. Modern Austria economy features include highly developed agricultural sector, a large service sector.