A solid substance is supplied heat at a constant rate and the variation of temperatuc with heat input is shown in the figurc Choose the correct statement.
(a) $A B$ and $C D$ represent changes of phase from liquid to vapour and from solid to liquid respectively.
(b) The latent heat of vaporization is half the latent heat of fusion.
(c) The spocific heat in the solid state is less than that in the liquid state.
(d) The spceilic heat in the solid state is more than that in the liquid state.