We can easily forgive a child who is afraid of the dark;the real tragedy of life is when men are afraid of the light. -Plato
He chose the correct answer, but whether by luck or by skill I don't know.
2. Used to introduce a yes-or-no interrogative content clause (indirect question) that consists of a single possibility, and indicate uncertainty over it; if, whether or not.
Do you know whether he's coming?
3. Used to introduce multiple alternative possibilities, and indicate the irrelevance of which is the case; regardless of whether, no matter whether.
He's coming, whether you like it or not.