Solution
The Fork in the Road
Show the problem again
You reach a fork: one road leads to safety, the other to doom. A guard stands there who is either a knight (always tells the truth) or a knave (always lies), but you don't know which. What is the minimum number of yes/no questions that guarantees you identify the safe road?
Worked solution
The answer is 1. Ask: "If I asked you whether the left road is safe, would you say yes?" Then trust the answer. The embedded-question trick makes lies cancel: a knight answers truthfully, and a knave lies about their own lie, producing the true answer either way. The classic alternative ("Which road would the other type of guard point to?") always indicates the wrong road (truth about a lie, or lie about the truth), so you take the opposite.
Source: Classic knights-and-knaves puzzle of the kind popularised by Raymond Smullyan. Statement written for AxiomIQ.