The correct option is B deviation.
The angle between the incident ray and the emergent ray of a prism is called angle of deviation.
In a prism refraction takes place at the two faces of prism. The incident ray strikes the first face, refracted ray travels through the prism and strikes the second face and emerges out of the prism as emergent ray. Angle of deviation is the change in the direction of the incident ray due to the optical medium.