Which Is NOT True of Mass Spectrometers

Which is NOT true of mass spectrometers?

A) Double-focusing mass spectrometers couple an electric sector to a magnetic sector to increase the resolution to ~10⁵.
B) Transmission quadrupole mass spectrometers select ions by applying a constant voltage and a radio-frequency oscillating voltage to the four parallel metal rods.
C) Orbitrap mass spectrometers do not require magnetic or radio-frequency fields to measure m/z.
D) Quadrupole mass spectrometers operate at constant resolving power.
E) The time-of-flight mass spectrometer employs a reflectron to group ions with the same m/z,regardless of initial kinetic energy.