Respuesta :
The answer would be a. Repairing, because "fiddling with" implies the same thing as "tinkering with" does, "selling" completely changes the meaning of the sentence, and "messing with" implies that he is even less skilled than "tinkering with" implies. Repairing things almost always takes skill.
The correct answer is B.To tinker with is the same as to fiddle with which means to handle something casually