What is a unique property of watercolor pencils?

Watercolor pencils possess the unique property of dissolving in water, allowing artists to create a watercolor effect. This characteristic enables users to apply the pigment with the pencil dry and then use a wet brush to activate the color, blending it seamlessly into washes or gradients reminiscent of traditional watercolor paints. This versatility makes watercolor pencils attractive for various artistic techniques, combining the precision of pencil drawing with the fluidity of watercolor paint.

In contrast, the options describing pastel colors, the inability to utilize them wet, or their primary use for sketching do not accurately reflect the main feature of watercolor pencils. Each of these aspects does not acknowledge the fundamental capability of these pencils that distinguishes them from standard colored pencils or other drawing tools.