Final answer:
The term 'tree farmer' regarding President Roosevelt indicates his keen interest and substantial knowledge in trees and conservation, evidence of which can be seen in the substantial expansion of forest reserves and establishment of wildlife sanctuaries during his presidency. The correct option is D.
Step-by-step explanation:
As it is used in line 7 to describe President Roosevelt, the term "tree farmer" most nearly means that Roosevelt: D. had a great interest in trees and knew a good deal about them. This description acknowledges Roosevelt's long-standing dedication to conservation, reflected in his policy decisions and his personal interests.
Roosevelt shared a perspective similar to Gifford Pinchot, the first chief of the U.S. Forest Service, in the scientific management of government lands and advocated for the conservation of natural resources.
Roosevelt's administration saw a significant expansion in the nation's forest reserves and he set aside 148 million acres of forest reserves, established over 50 wildlife sanctuaries, and made efforts to include several national parks. His aim was to ensure the long-term availability of lumber and other natural resources while conserving the environment, reinforcing his interest and knowledge as a "tree farmer."