Answer:
Explanation: The heat emission mechanism that makes the athlete cool down faster in water is option A, Heat convection.
Heat convection is the transfer of heat through the movement of a fluid or gas. When the athlete is submerged in water, the water surrounding the athlete's body is cooler than the athlete's body temperature, so heat is transferred from the athlete's body to the surrounding water through convection. This causes the athlete's body temperature to decrease, making them cool down faster.
Heat conduction is the transfer of heat through direct contact between two objects. This mechanism does not apply in this case as the heat is transferred from the athlete to water not by direct contact but by movement of fluid.
Heat exchange is the transfer of heat between two substances or systems. It's a general term but in this case, it is referring to the heat exchange through convection.
Sweat evaporation is the process of sweat turning from a liquid to a gas. As the athlete is submerged in water, sweat evaporation will not play any role in cooling down the athlete.