The necessary heat of evaporation is extracted from the sweat itself, which leads to a heat transfer from the liquid into the gaseous state. This results in a cooling effect (called evaporative cooling) that helps to maintain body temperature and cools the body down when it gets too hot.
Option a, b and c are examples of not practicing proper hygiene and they increase the chances of you getting diseases. Option D is the only example that practices proper hygiene.
