What three groups make up the total casualty numbers

Nationalsim led to major conflicts following world war1 especially when

Match the people with the appropriate description. vernon and irene castle arthur murray fred astaire willi ninja a. stylized the forms of ballroom dance by incorporating other dance forms b. responsible for renewing the influence of ballroom dance in america c. godfather of vogue danced. responsible for standardization/teaching of steps leading to spread of ballroom dance education

Why did metternich think nationalism threatened the austrian empire?