(Farmer : Plough) , (Butcher : Chopper) , (Author : Book) , (Jockey : Tack) , (Lumberjack : Axe)
Option:
Justification: In all other pairs, second is the tool used by the first.

(Farmer : Plough) , (Butcher : Chopper) , (Author : Book) , (Jockey : Tack) , (Lumberjack : Axe)
Justification: In all other pairs, second is the tool used by the first.