Select the group of words from the given options that shares a similar…

This item follows the pattern Instrument : Physical quantity it measures : Standard unit of that quantity. For the pattern to hold, all three elements of a pair must correctly correspond to one another - the instrument must actually measure the stated quantity, and the stated unit must actually be the standard unit for that quantity.

In the given set, a thermometer measures temperature, and temperature is expressed in degrees - the instrument, the quantity, and the unit all match. Checking the options against the same triad: a scale measures length, and length is expressed in meters, so every element of this pair corresponds correctly, exactly mirroring the given relationship.

• Voltmeter : Current : Ampere - a voltmeter actually measures potential difference (voltage), not current, so the instrument and the quantity named here do not correspond.

• Ammeter : Potential : Volt - an ammeter actually measures current, not potential difference, so the instrument and the quantity named here do not correspond.

• Barometer : Pressure : Watt - a barometer does measure pressure, but pressure is expressed in units such as the pascal, not the watt, which is the unit of power, so the quantity and unit named here do not correspond.

Scale : Length : Meter is the only pair where the instrument, the quantity it measures, and the unit all correctly correspond, so it shares the same relationship as the given set.