The light emitted by an incandescent element produces: ~a unique continuous spectrum ~an emission line spectrum ~a spectrum identical to the hydrogen atom ~a spectrum of one unique wavelength

It produces a line emission spectrum. I hope that helps.

The correct answer should be "electrons orbit the nucleus in circular motions exactly as shown on the classic bohr model."

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.