A lump of ice at $-20^\circ\text{C}$ is warmed until it becomes steam. The graph showing temperature plotted against thermal energy absorbed is given. The latent heat of fusion of ice is $340\ \text{kJ kg}^{-1}$. What is the mass of the ice?
- A$1.0\ \text{kg}$
- B$2.0\ \text{kg}$
- C$3.0\ \text{kg}$
- D$4.0\ \text{kg}$