The correct answer is D) Cumulatively compounded long-shunt. In a cumulatively compounded long-shunt DC generator, the series field winding is connected in series with the armature, and the shunt field winding is connected in parallel with both the armature and the series field. This configuration results in the series field and shunt field windings adding their respective magnetic fields, which increases the overall excitation of the generator. The "long-shunt" refers to the shunt field winding being connected across the entire generator output. The other options are incorrect because: A) is a cumulatively compounded short-shunt configuration, B) is a differentially compounded short-shunt configuration, and C) is a differentially compounded long-shunt configuration, all of which differ from the configuration shown in figure "B" of the illustration.