In "Adoration of the Shepherds" by Nicolaes Maes, the most prominent feature is likely the contrast in value between light and dark. This is typical in paintings from this period, especially in scenes involving the divine or religious themes, where the use of chiaroscuro (the contrast between light and shadow) is employed to highlight figures and create a dramatic effect.
While the painting may feature warm colors and textures, the strong contrast in value is a defining characteristic that aligns with the style of the work. Therefore, the best response would be:
contrast in value between light and dark.