To model means to give shape or form to something. According to a dictionary definition, modeling is "the technique of rendering the illusion of volume on a two-dimensional surface by shading."
Assuming you have this in mind, you can see some exquisite shading in the painting done by Michelangelo, especially on the blue skirt, or cloth this person is wearing. In order to create something more vivid and life-like, Michelangelo applied this technique to most of his paintings, and it is obvious in this one as well.
It seems that you have missed the given options for this question, but anyway, the correct answer would be BALANCE. The classical idea that is embodied in the theme of Haydn's "Surprise" Symphony is balance. Hope this is the answer that you are looking for.
