The correct answer is B) shunt wound where the field is separately excited from a non-controlled rectifier. In a DC diesel-electric drive system, shunt wound motors are commonly used where the field winding is excited separately from the main armature winding. This allows for independent control of the field current, which is typically provided by a non-controlled rectifier rather than a controlled rectifier. The other options are incorrect because: A) a controlled rectifier would be used for a separately excited field, C) a series wound motor has the field winding in series with the armature, and D) a shunt wound motor has the field winding in parallel with the armature.