Margaret has an idea for a painting. she wants to present a close-up view of the inside of the sun as a viewer might see it through a cut-away portion of the sun’s surface. she should use the
technique of painting.

She should use the Illusionistic technique of painting.

Explanation:

Illusionistic painting (or architectural painting) is a term for painting where with the help of perspective and the use of architectural elements combined with the implementation of light and shadow artist creates a 3D illusion. To put it more simply, this technique often uses light, shadow and perspective to manipulate the visual response.

It is frequently used to create the illusion of an open sky, such as with the Oculus in Andrea Mantegna's Camera degli Sposi.  

Illusionism in history of art means either the artistic tradition in which artists create a work of art that appears to share the physical space with the viewer or more widely the attempt to represent physical appearances precisely which is also called mimesis.