57. with reference to thermal behaviour of any material the "triple point" is (a) the temperature at which the material exists in all the three phases, i.e. vap

57. With reference to thermal behaviour of any material the "Triple point" is (A) the temperature at which the material exists in all the three phases, i.e. vapour, liquid and solid at the same time (B) the pressure at which the material exists in all the three phases, i.e. vapour, liquid and solid at the same time (C) the temperature at which the material exists in only liquid and solid phase simultaneously (D) the material exists in the solid phase only