a prism is a three-dimensional shape that has two bases that are parallel and the same size and shape. The prism's sides are all parallelograms. A classic pup tent is a triangular prism. In optics, a prism is a piece of glass, quartz, plastic, or other material that can be used to refract light.
Im sorry I really dont get the question maybe you can rephrase it
The alternation between orchestral refrains and virtuosic outbursts by the soloist(s) is known as fast movements in Baroque concerto as there is three movements in Baroque concerto, fast-slow-fast.Ritornello Form is used in the first and last movements of baroque concerto and this form every part is different but the passage sounds like it is similar to the other passage before that and the alteration is also included in this.
The picture is not that clear but A is probably the answer.