Final answer:
The Progressive reformers blamed juvenile crime on factors such as poverty, overcrowding, immigration, and lack of parental guidance.
Step-by-step explanation:
The group of reformers who blamed juvenile crime on factors such as exposure to poverty, overcrowding, immigration, and lack of parental guidance were the Progressive reformers. They believed that addressing these social and economic issues could help reduce juvenile delinquency. For example, they advocated for the implementation of child labor laws, improved housing conditions, and support for immigrant families.