$A$ solid cube of mass $m$ at a temperature $\theta_0$ is heated at a constant rate. It becomes liquid at temperature $\theta_1$ and vapour at temperature $\theta_2$. Let $s_1$ and $s_2$ be specific heats in its solid and liquid states respectively. If $L_f$ and $L_v$ are latent heats of fusion and vaporisation respectively,then the minimum heat energy supplied to the cube until it vaporises is

• A
  $m s_1(\theta_1-\theta_0)+m s_2(\theta_2-\theta_1)$
• B
  $m L_f+m s_2(\theta_2-\theta_1)+m L_v$
• C
  $m s_1(\theta_1-\theta_0)+m L_f+m s_2(\theta_2-\theta_1)+m L_v$
• D
  $m s_1(\theta_1-\theta_0)+m L_f+m s_2(\theta_2-\theta_0)+m L_v$