The correct answer is D) armature. In a series wound motor, the current passing through the field windings also passes through the armature. This is because in a series wound motor, the field windings and the armature are connected in series, forming a single circuit. The current that flows through the field windings is the same current that flows through the armature, which is why the correct answer is the armature. The other answer choices are incorrect because: A) a reactance comparator is not a component in a series wound motor, B) the shunt field is a separate winding not directly connected to the armature in a series wound motor, and C) the laminations are part of the motor's construction, not a component through which the current flows.