In painting, medium is
a. the choice of liquid or gas that is added to a pigment.
b. the substance that is added to a color in order to application.
c. a media that consists of natural or synthetic mineral or plant substances.
d. the pigment that mixed with a binder of hot wax and fixed with a heat application

c. a media that consists of natural or synthetic mineral or plant substances
In painting, medium is the term used for the substance that binds the pigment in paint. Synthetic substance is used in acrylic paint, natural oil for oil paints, and egg yolk for tempera.
The word "medium" can also be used to change the paint's consistency, or to describe a category of painting or merely the type of paint used.

Answerthey showed a domestic scene from christ's life on earth