What is algin?

A. Diatomaceous earth used as an insulating material

B. Brown algae

C. A substance produced by brown algae used to thicken foods.

D. Diatom shells

Any hydrophilic, colloidal substance found in or obtained from various kelps, as alginic acid or one of its soluble salts.

Tell me if you don't understand what I put down and this is the definitions.

I think its D

C. A substance produced by brown algae used to thicken foods