The correct answer is C. More than no-load terminal voltage.
A level compounded D.C. generator is a type of generator that has a constant voltage output regardless of the load. This is achieved by using a field winding that is connected in series with the armature winding. The field winding creates a magnetic field that interacts with the armature winding to produce an electric current. The amount of current produced is proportional to the strength of the magnetic field.
When the generator is not loaded, the field winding is energized and the magnetic field is strong. This produces a high voltage output. When the generator is loaded, the armature winding draws current from the field winding. This reduces the strength of the magnetic field and the voltage output decreases. However, the voltage output does not decrease to zero. The voltage output remains above the no-load voltage because the field winding is still energized.
The options A, B, and D are incorrect. Option A is incorrect because the full load terminal voltage is not negligibly low. Option B is incorrect because the full load terminal voltage is not equal to the no-load terminal voltage. Option D is incorrect because the full load terminal voltage is not less than the no-load terminal voltage.