Well you should assume that both guards follow the rules all time. Meaning that the initial setup of the rules cannot be trusted, because who knows if the talking Guard is lieing or not. If one does tell nothing but the truth this must be the one explaining the rules.
However if I remember correctly it was setup that one will answer the truth while the other one will deceive me. Meaning he might tell the truth if it confused me.
So no question might work.
Simple logic twisting really. Ask any guard what other guard would say, negate that answer and you got the right answer.
How though?
A truth B lies
Ask A: answer is No (truth)
Ask B: answers is No (lies)
Let’s suppose A always lies and B always tells the truth.
You ask A what B would say this being a correct path. In this case B can’t lie and will tell True, A will then lie about that and will say False, you negate False -> True.
Say you ask B what A would say this being a correct path. In this case A always lies and if road is correct they will say False, B who can’t lie will tell you A would say False, you negate that -> True.