Which of these is an example of how engineers have contributed to society? A. Our current understanding of viruses
B. The theoretical mathematics describing the orbits of planets
around the sun
C. The seven-mile bridge that spans across the Gulf of Mexico to
connect two cities of the Florida Keys
D. Nomadic tribes traveling in search of food to hunt and gather

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.