AP Environmental Science

Answer: C - John Muir is best known for founding the Sierra Club.

Key Takeaway: Best known for founding the Sierra Club, one of the most important conservation organizations in the United States, John Muir was a greatly influential naturalist and author. As an early advocate for wilderness preservation, his actions and writings helped to save many beautiful natural areas, such as Yosemite Valley, Sequoia National Park, and areas of the Sierra Nevada Mountains in California.