If a single-phase capacitor start induction motor fails to start, but instead hums without starting, what is most likely to be the problem?

Correct Answer: Option B — an open start capacitor

An open start capacitor removes the necessary phase shift for auxiliary winding torque generation, causing single-phase motors to stall and hum under applied line voltage. IEEE 45 electrical maintenance procedures specify capacitor capacitance and continuity testing during motor diagnostics.