The correct answer is C. Alizarin.
A natural dye is a dye that is derived from plants, animals, or minerals. Natural dyes have been used for centuries to color textiles, food, and other materials. They are often considered to be more environmentally friendly than synthetic dyes, and they can produce a wider range of colors.
Crystal violet is a synthetic dye that is used to stain bacteria and other cells. It is a deep purple color and is soluble in water.
Aniline blue is a synthetic dye that is used to color textiles and paper. It is a blue-green color and is soluble in water.
Phenolphthalein is a synthetic dye that is used as an indicator in chemistry. It is colorless in acidic solutions and pink in basic solutions.
Alizarin is a natural dye that is extracted from the roots of the madder plant. It is a red-purple color and is soluble in water.