Which one of the following devices is most often used for measuring opposition to current flow in a circuit? A. Ammeter B. Voltmeter C. Ohmmeter D. Wattmeter E. None of the above

The correct answer is C. Ohmmeter.

An ohmmeter is a device used to measure electrical resistance. It is a type of multimeter that can also measure voltage and current. Ohmmeters are typically used to troubleshoot electrical problems, such as finding a short circuit or open circuit.

An ammeter is a device used to measure electric current. It is typically connected in series with the circuit being measured. Ammeters are typically used to measure the current flowing through a circuit, such as the current flowing through a motor or a light bulb.

A voltmeter is a device used to measure electric potential difference. It is typically connected in parallel with the circuit being measured. Voltmeters are typically used to measure the voltage across a circuit component, such as the voltage across a resistor or a capacitor.

A wattmeter is a device used to measure electric power. It is typically connected in series with the circuit being measured. Wattmeters are typically used to measure the power consumed by a circuit, such as the power consumed by a motor or a light bulb.

None of the above is the correct answer because it is not a device that is used to measure opposition to current flow in a circuit.