The general principle is: G -> not API We know that the contrapositive of this is: API -> not G
The argument in the passage proceeds by invoking the sufficient condition of the contrapositive (API) to conclude the necessary condition of the contrapositive (not G), which is the valid contrapositive argument structure. Since this is a parallel reasoning question, we should look for an answer choice that also uses the valid contrapositive argument structure.
Does that make sense? Please let us know if you have any other questions!
