What does theodore roosevelt claim in the excerpt?

Theodore Roosevelt, 26th President of the United States, was one of the most important and effective environmental leaders in American history. Beginning in the 1880s and culminating with his Presidency (1901-1909), his leadership of the emerging American conservation movement was instrumental in preserving hundreds of millions of acres of natural and historic treasures, including forests, wetlands, endangered species, native ruins, and “natural wonders” like the Grand Canyon

Istrongly feel d is the answer but c is also a strong possibility