A cinematographer can create a believable scene in nature through multiple methods, but the most critical aspects would be:
C. through lighting techniques that mimic natural light - Good lighting is essential in capturing the essence of natural environments. The cinematographer can use techniques to replicate the quality, direction, and color of natural light, enhancing realism.
However, A. through research of plants and animals is also important, as understanding the setting's natural elements can help in creating authentic visuals.
While B. through adjustment of props and D. through close-up filming techniques can contribute to visual storytelling, they are more about enhancing specific scenes rather than establishing overall believability in nature.
In summary, option C stands out as the most impactful method for creating a believable scene in nature.