The room can be cooled effectively by releasing compressed gas. When compressed gas is released into a room, it undergoes expansion. This expansion process absorbs heat from the surrounding environment due to the endothermic nature of gas expansion, thereby cooling the air in the room. This principle is the foundation of air conditioning and refrigeration systems. As the compressed gas expands, it absorbs thermal energy from the room’s air, resulting in a drop in temperature. The cooling effect is utilized in various cooling devices, such as air conditioners and refrigerators, where the refrigerant gas cycles through compression and expansion phases to maintain a cool environment. This method of cooling is efficient and widely used in residential, commercial, and industrial applications. Therefore, the correct answer is [B] by releasing compressed gas.