Which is a temporary, not permanent, way to change hair color for a single styling session or short term?

A temporary color (such as a temporary rinse, spray, or some wash-out products) changes the hair color by mostly coating the surface/cuticle and washing out after one or a few shampoos, making it a temporary change. Permanent color penetrates the cortex and lasts until it grows out. (Relaxers and perms change texture, not color.) Distinguishing temporary surface color from permanent color that enters the cortex connects color types to hair structure, a theme the exam reinforces, while detailed application is learned in training.