The correct option is
C t3∘CFrom the curve, boiling point is to3C
In part AB, state is solid and temperature is rising.
In part BC, there is change of state from solid to liquid, i.e., this stage is melting, without change in temperature.
In part CD, state is liquid and temperature is rising.
In part DE, there is change of state from liquid to gas, i.e., this stage is vaporization, without change in temperature.
In part EF, state is gas and temperature is rising.