Who was a major proponent of the preservation of the Grand Canyon?

The correct choice is President Theodore Roosevelt, who was a pivotal figure in the conservation movement during the early 20th century. His administration placed a strong emphasis on the preservation of natural resources and protected vast tracts of land. In 1908, Roosevelt designated the Grand Canyon as a national monument, which was a key step in safeguarding this remarkable landscape from development and exploitation. He believed in the importance of protecting natural spaces for future generations to experience and enjoy, setting a precedent for national parks and conservation efforts that would follow.

This focus on preservation was part of Roosevelt's larger legacy of environmental stewardship, where he established five national parks, 18 national monuments, and a number of wildlife refuges, significantly expanding the United States' protected lands during his presidency. The actions he took not only helped to preserve the Grand Canyon but also laid the foundation for the ongoing conservation efforts that promote the protection of natural areas across the country.