Which motor improves power factor

A motor that improves power factor is a Synchronous motor (over excited). Power factor is the ratio of real power (measured in watts) to apparent power (measured in volt-amperes). A motor with a low power factor draws more current than is necessary to perform the desired work, which results in higher energy costs and lower system efficiency. By contrast, a synchronous motor with overexcitation can correct the power factor by adjusting the amount of reactive power that it draws from the power grid.

Option A, Induction motor, and Option B, Slip ring motor, do not have the capability to adjust the power factor.

Therefore, the answer to this question is Option C, Synchronous motor (over excited).