A spring balance calibrated on Earth (where 1kgf=9.8N) is taken to Planet X, where the acceleration due to gravity is 12m/s2. When an object is hung from the balance, it shows a reading of 15kgf. What is the mass of the object?
(a) 15kg
(b) 12.3kg
(c) 18.4kg
(d) 14.7kg