The two categories are....Mechanical Malfunction and CFIT.
You can take your pick of any number of events that fall under Mechanical Malfunction or a single choice under the alternative.
Remember the Foot Ball Stadium crash that killed the Team Owner....how many folks went for the Pilot Error option when it was actually a Tail Rotor Control mechanical failure?
We had a real time video of that one and all of the Keyboard Investigators got it wrong early on.