The preparatory drawing in mural paintings is known as:

The correct answer is C. Rekha.

Rekha is the preparatory drawing in mural paintings. It is a thin line drawn on the wall with a charcoal or chalk stick. The rekha is used to outline the figures and objects in the painting. It is also used to indicate the perspective and proportions of the painting.

The other options are incorrect.

• Kolam is a traditional Indian art form that involves drawing intricate patterns on the ground with rice flour or sand.
• Chitrakala is the Indian art of painting. It is a broad term that encompasses a variety of styles and techniques.
• Varna is a Sanskrit word that means “color” or “caste.” It is also used to refer to the four main social classes in Hinduism.