The most appropriate response when critiquing a piece of art would depend on the specific focus of your critique. However, if I had to choose one that is generally applicable and allows for a broader analysis, I would suggest:
Judge the creative expression of the piece.
This response allows you to consider various elements of the artwork, including the choice of materials (like oil pastels), the portrayal of objects (realism), and any historical or emotional implications involved in the creative process.