Answer:
The correct answer is D. The group that is focused on protecting wilderness areas of the United States is the Sierra Club.
Step-by-step explanation:
Sierra Club is one of the oldest, largest and most influential environmental organizations in the United States. It was founded on May 28, 1892, in San Francisco, California, by conservationist John Muir, who became its first president.
Traditionally associated with the progressive movement, the club was one of the first large-scale environmental conservation organizations in the world, and promoted green policies. Recent proposals by the club include green energy and the prevention of climate change, although the preservation of forests and mitigation of pollution are still some priority policies.