The temperature of a sample of liquid water changes from 50°C to 30°C. Which statement best explains the change that must happen at the molecular level?
O The molecules move more quickly and their average kinetic energy increases.
O The molecules move more slowly and their average kinetic energy decreases.
O The molecules move more quickly and their average kinetic energy decreases.
O The molecules move more slowly and their average kinetic energy increases.

The answer is b because a,c,and d are opinons

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.