The correct answer is B. Lagging.
Power factor is the ratio of real power to apparent power. Real power is the actual power that is used to do work, while apparent power is the total power that is supplied to the load. The power factor of an industrial load is generally lagging because the load is inductive. Inductive loads store energy in a magnetic field, and this stored energy causes the current to lag behind the voltage.
Option A, unity, is not correct because the power factor of an industrial load is generally lagging. Option C, leading, is not correct because the power factor of an industrial load is generally lagging. Option D, zero, is not correct because the power factor of an industrial load is generally greater than zero.