Final answer:
The detail that does not help figure out the theme is a child observing a sunrise, as it does not directly address human activity and its environmental consequences, unlike the other options that are linked to environmental themes.
Step-by-step explanation:
The detail that does NOT help you figure out the theme is C. A child observing a sunrise for the first time. While the other options (A. If we don't act now, the beauty of nature will disappear, B. A group of activists planting trees in a deforested area, and D. A story about a factory polluting a river) directly relate to environmental issues and human impacts on nature, a child observing a sunrise is a more general experience that does not specifically address the theme of human activity and its environmental consequences.
Themes in literature are overarching ideas or messages conveyed by the stories, characters, and actions within a piece of writing. In the context of environmental literature or discussions, themes often revolve around the relationship between humans and the natural world, the consequences of human actions on ecosystems, and the need for conservation and sustainability. Biodiversity, environmental justice, and the presumptive principle are critical in understanding these themes.