What is voltage measured in?

Voltage is measured in volts, and a voltmeter is the device specifically designed to measure electrical potential difference or voltage in a circuit. When using a voltmeter, calculations reflect the amount of voltage present between two points in an electrical system, which directly corresponds to how much electrical energy is available to push an electric current through a circuit.

Kelvins is a unit of measurement for temperature, not electrical potential. An ammeter is used to measure current, the flow of electric charge, rather than voltage. An ohmmeter measures resistance in an electrical component, not voltage. Thus, the voltmeter is the most appropriate and accurate device for measuring voltage, which makes it the correct answer in this context.