The correct answer is B) Formalism.
The aesthetic theory that Picasso portrait on Gertrude Stain adhere to Formalism.
The other options of the question were a) emotionalism and c) imitationism.
Formalism in art is the analysis of art comparing its form and style. It gives emphasis to color, texture, shape, and line, as an element of the composition of the piece of art. It does not consider the content of the art of the historical context. Formalism establishes that in the work of art is everything you need to understand the meaning.
The portrait on Gertrude Stain was a work of Spanish painter Pablo Picasso, finished in 1906.