‘Hengul Haital’ refers to a traditional Assamese painting medium made from:

The correct answer is: a) Natural pigments mixed with eggshell.

Hengul Haital is a traditional Assamese painting medium made from natural pigments mixed with eggshell. The pigments are derived from plants, minerals, and animals, and the eggshell is used as a binder. The medium is applied to cloth or paper with a brush or a stylus. Hengul Haital paintings are often brightly colored and depict scenes from nature or religious stories.

Option b) is incorrect because vegetable dyes are not used in Hengul Haital. Option c) is incorrect because mineral colors are not used in Hengul Haital. Option d) is incorrect because charcoal is not used in Hengul Haital.