Pop Quiz: Clothing Au Naturel
Answer: D -- All of these fibers are cellulose derived, although not all of them are naturally occurring.
Linen comes from the fibers of the flax plant, the same one that gives flaxseed to your bread, and linseed oil to your furniture.
Rayon is "less natural", and is made by dissolving cellulose into a solution, and then extruding it through hundreds of tiny holes into sulfuric acid, which solidifies it into fibers:
Tencel is made in a similar method to Rayon, although the solvent used can be reclaimed, making the process significantly less polluting: