Answer
B. Progressives believed that the assimilation of immigrants would make them less loyal citizens
Step-by-step explanation
Progressives strongly believed in American ideas and progress. These individuals believed that ethnics and class problems were as a result of self/private interest over the interest of many people that led to corruption and a spoiled political system. Progressives proposed the unification of all classes and ethnic groups to form a single middle class with people with similar traits.