Question

when measuring resistance with an ohmmeter, a observe polarity. b disconnect power. c add power. d insulate probes.

Explanation:

When using an ohmmeter to measure resistance, it is crucial to disconnect power from the circuit being measured. This is to prevent damage to the ohmmeter and to get an accurate resistance reading. Resistance is an inherent property of a component or circuit element and should be measured without the influence of an external voltage source present in the circuit. Polarity is not a concern for resistors in most basic resistance - measuring scenarios. Adding power is the opposite of what should be done, and insulating the probes is not a necessary step for basic resistance measurement.

Answer:

B. disconnect power.