It is important to realize that an element’s line spectrum can include emissions at wavelengths throughout the electromagnetic spectrum including ultraviolet, visible, and infrared. According to the procedure in Part 2, where will you be collecting data on hydrogen and helium’s line spectra?

D)can be increased in a closed system

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.