The area of hysteresis loop of a material is equivalent to 250 J. When 10 kg material is magnetised by an alternating field of 50 Hz, then energy lost in one hour, if the density of material is $7.5 \mathrm{g}/{\mathrm{cm}}^3$, will be

• A

  $6 \mathrm{x} {10}^4 \mathrm{J}$

• B

  $6 \mathrm{x} {10}^4 \mathrm{erg}$

• C

  $3 \mathrm{x} {10}^2 \mathrm{J}$

• D

  $3 \mathrm{x} {10}^2 \mathrm{erg}$