The answer is D. Richard Ballinger.
John Muir was a Scottish man who was known for his conservationist policies. He is known as the "Father of the National Parks."
Teddy Roosevelt was a huge conservationist as well. Roosevelt's Three C's policy consisted of: consumer protection laws, controlling of corporations, and conservation of natural resources.
Gifford Pinchot was the head of the US Forest Service under Roosevelt, helping to ensure that federal lands were protected from businesses and individuals who wanted to buy this territory for personal use.
This is why Richard Ballinger is the correct answer.