The correct answer is C.
John Muir ( also known as John of the Mountains and Father of the National Parks ), was a Scottish-American naturalist, book author, environmental philosopher and an avid advocate for the preservation of wilderness in The United States.
In his books and essays he described his adventures in nature, especially in the Sierra Nevada. With his dedicated work he helped to preserve many wilderness areas such as the Yosemite Valley, the Sequoia National Park and many others.
Muir was also the co-founder of the Sierra Club which is a prominent conservation organization.
Muir's life work has been inspiration to many politicians, congressmen and leaders to take action to preserve large nature areas.