Kelvin's double bridge is used to measure low resistances becauseit had high sensitivitythere is no thermoelectric emfresistance variation due to temperatureeffect of contact lead resistances is eliminatednone of the above

Kelvin's double bridge is used to measure low resistances because the effect of contact lead resistances is eliminated. This method provides a high degree of accuracy by compensating for the resistance of the leads connecting the meter to the component being tested. Therefore, the answer is "effect of contact lead resistances is eliminated".