Which of the Following Statements About Mass Spectrometry Is True

Which of the following statements about mass spectrometry is true?

A) The species being studied by mass spectrometry must carry a negative charge.
B) Mass spectrometry usually generates a mass spectrum with a single peak.
C) The molecular ion peak in a mass spectrum can be used to distinguish between structural isomers.
D) The sample being studied by mass spectrometry must be a vapour.
E) Isotopes of the same element generate the same peak in a mass spectrum.