How is inductance primarily measured?

Inductance is primarily measured in henries. A henry is the SI unit of inductance and is defined as the amount of inductance required to produce an electromotive force of one volt when the current through the inductor changes at a rate of one ampere per second. This relationship highlights how inductance quantifies the ability of an inductor to store energy in a magnetic field when electrical current passes through it.

The other options represent different electrical measurements: volts measure electric potential, amperes measure current, and ohms represent resistance. Each of these units is important in various contexts within electrical circuits, but they do not apply to the measurement of inductance itself. Thus, henries is the only correct unit for inductance.