Laaaate but i just worked it out.
There are no neutral answers, just correct and incorrect ones. However the answers to some questions change depending on the difficulty. I just use save states and everytime no matter where the question was it would produce 2 wrong and 1 right answer.
The main guy is the driving intructor dude. The ones that change are the ones about the train, where teh answer is it will be late on easy and medium but jump the train on hard difficulty. Also the question about taking over the car changes.....i think hard the answer is blow it up, while the other difficulties its honk your horn till it lets you pass.
The change i guess is a mistake but it happens on most communication screens if not all...seems unlikely they would just randomly change the answers though.