This question tests AP German Language and Culture skills: explaining how data illustrates cultural phenomena. Understanding cultural data involves recognizing trends and inferring cultural significance from statistical information. The statistics show dialect usage patterns in the context of standard language promotion in schools. Choice C is correct because it accurately reflects the nuanced trend: decreasing frequent dialect use indicates standardization without complete dialect elimination. Choice A is incorrect because it claims standard German has been largely displaced, which contradicts the standardization trend promoted by educational institutions. To help students: Encourage them to recognize balanced interpretations of linguistic data. Practice analyzing how educational policies influence language use while regional varieties persist in certain contexts.