What Prompted Early Scientists to Propose That the Ray of the Cathode

Multiple Choice

What prompted early scientists to propose that the ray of the cathode ray tube was actually a negatively charged particle?

A) The ray was present regardless of gas, or even without a gas.
B) The ray was attracted to positively charge electric plates.
C) The ray was not seen from the positively charged anode.
D) The ray could be diverted by a magnetic field.
E) The ray would change colors depending on which gas was used inside the tube.