To determine which natural resource was used for the drawing, we would need additional context regarding the medium or technique visible in the drawing. However, based on the options:
- A. Clay: Typically used for sculpture or pottery, not drawing.
- B. Wax-based colored pencils: These are synthetic and not a natural resource.
- C. Graphite pencil: Graphite is a natural resource and commonly used for drawing.
- D. Watercolors: While this can be made from natural pigments, it often includes synthetic components.
If the drawing is specifically created using a pencil, then the answer would be C. Graphite pencil. If it were a painting using pigments, it might also be D. Watercolors, depending on the specific materials used.