What should be done before filling a background with acrylic colour?

Correct answer: Prepare enough colour mixture

The governing concept is preparation for consistent coverage. Before filling a large background, enough acrylic colour mixture should be prepared so that the same shade can be used across the area. This reduces visible differences between sections and avoids stopping midway to remix the colour. Making a new colour for every stroke creates inconsistency, oil can interfere with the surface, and a dirty brush contaminates the paint. Therefore option A is correct.