ANS:B - condenser

Heat release during phase change is observed in the case of a/an condenser. In a condenser, the vapor phase of a substance is cooled and condensed into the liquid phase, releasing heat in the process. This heat release occurs as the vapor loses thermal energy and transitions to the liquid phase, resulting in a decrease in temperature. In contrast, a boiler and an evaporator are both components of systems where phase change involves heat absorption rather than heat release. In a boiler, liquid water is heated to generate steam, absorbing heat in the process. In an evaporator, a liquid substance is heated to evaporate into vapor, also absorbing heat. Therefore, the correct answer is (b) condenser.