Bateman stares into the mirror. The masque has dried, giving his face a strange distorted look as if it has been wrapped in plastic. He begins slowly peeling the gel masque off his face.

A is a light retinol. B is niacinamide. C is C. D you should be making from sunlight (or getting from supplements). E is E. Water is moisturiser.

Pretty much all evidence-based skincare comes down to providing these vitamins (plus water) to your skin.