This is the standard answer I have seen (and also used myself in trivia in the past), but I think it has to be altered.
Since we are discussing interference, it got me thinking that fielder's interference is perhaps not the same as catcher's interference.
So if the first base or pitcher blocked or grabbed the runner on the way to first base, that would be fielder's interference. .
So we keep 6 and change it to "Fielders Interference" rather than "Catchers Interference", or we create a seventh one.