The correct answer is B) 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 flowing through the field windings generates a magnetic field that interacts with the current in the armature, producing the torque that drives the motor. The other answer choices are incorrect because: A) a reactance comparator is not a component in a series wound motor, C) the shunt field is a separate winding that is not in the same circuit as the armature, and D) the laminations are part of the motor's construction but do not carry the current.