Answer:
religious groups
Explanation:
Robert Putnam is an American political scientist. He is most known for his controversial publication Bowling Alone. According to the publication Bowling Alone, United States has faced a downfall in civic, social, and political life (social capital).
According to Robert Putnam (2000), membership in religious groups was most closely associated with other forms of civic involvement, like voting, jury service, community projects, and giving to charity.