Correct option is A
Litmus is a natural dye that is extracted from certain species of lichen, a symbiotic organism that consists of a fungus and an alga. It is commonly used as an acid-base indicator in chemistry. When dissolved in water, litmus changes color depending on the pH of the solution: it turns red under acidic conditions and blue under basic (alkaline) conditions. This makes it a useful tool for determining the acidity or alkalinity of substances.
