Which of the following measures how closely the actual output voltage matches the expected theoretical level?

The measure that reflects how closely the actual output voltage aligns with the expected theoretical level is accuracy. Accuracy indicates the degree to which a measured value represents the true value or theoretical standard. In scenarios involving electrical measurements, achieving high accuracy means that the voltage being measured or outputted is very close to what is theoretically anticipated.

Precision, on the other hand, deals with the repeatability or consistency of measurements, not necessarily their correctness; it is possible to have precise measurements that are not accurate if they systematically deviate from the true value.

Resolution refers to the smallest change in a measured variable that can be detected by a measurement system, which does not directly address the conformity of the measured value to its expected level.

Stability pertains to how consistent a system is over time or under varying conditions, but again, it does not evaluate how closely measurements match theoretical expectations.

Thus, accuracy is the correct answer as it specifically measures the alignment of actual measurements with expected theoretical outputs.