Open - circuit voltage of 60 V and current of 160 A were the welding conditions for arc welding of a certain class of steel strip of thickness 10 mm. For arc welding of 5 mm thick strip of the same steel the welding voltage and current would be
(a) 60 V and 80 A (b) 120 V and 160 A
(c) 60 V and 40 A (d) 120 V and 40 A