Which of the following is a mask that forms a hard, rubber-like consistency, increases blood circulation, and firms the skin?

The mask that forms a hard, rubber-like consistency, increases blood circulation, and firms the skin is a modelage mask. Modelage masks are typically composed of a mixture of plaster and other ingredients that, when applied to the face, harden into a solid form. This transformation creates a thermal effect, promoting improved blood circulation in the skin. The firming effect can help to temporarily tighten and lift the skin, making it an excellent option for clients looking for rejuvenating treatments.

In contrast, other types of masks serve different purposes. Cream masks are usually moisturizing and nourishing, but do not harden or create a rubber-like consistency. Sheet masks are single-use fabric masks infused with serums; they deliver hydration and nutrients but do not provide the firmer structure associated with modelage masks. Clay masks are used primarily for their detoxifying properties; they help absorb excess oil and impurities but do not form a hard structure and thus lack the same benefits of increased circulation and skin firming typical of modelage masks.