Smoke : Fire — choose the pair below that shows exactly the same relation.

Smoke is the visible sign that betrays a fire, so the first word is the effect and the second the hidden cause. Fever works the same way: it is the outward sign of an illness beneath it. 'Cloud : Rain' and 'Match : Flame' both put the cause first and the effect second, which is the very order the given pair reverses. 'Wood : Ash' names a material and the residue left behind, and wood announces no ash.