Critical Reasoning

This one is already discussed somewhat in the parent forum. Bringing it here to re initiate the discussion:-

Metal ring excavated from seventh-century settlements in the western part of Mexico were made using the same techniques as those used by Ecuadorian artisans before and during that period. These techniques are sufficiently complex to make their independent development in both areas unlikely. Since the people of these two areas were in cultural contact, archeologists hypothesize that the metallurgical techniques used to make the rings found in Mexico were learned by Mexican artisans from Ecuadorian counterparts

Which of the following would it be most useful to establish in order to evaluate the archeologists hypothesis

A) Whether metal objects were traded from Ecuador to Western Mexico during the 7th century

B) Whether travel between Western Mexico and Ecuador in the seventh century would have been primarily by land or by sea

C) Whether Artisans from Western Mexico could have learned metallurgical techniques from their Ecuadorian counterparts without actually leaving Western Mexico

D) Whether metal tools were used in the seventh century settlements in Western Mexico

E) Whether any of the techniques used in the manufacture of the metal rings found in Western Mexico are still practiced among the artisans in Ecuador today


OA is A -- Now why is A superior to D here. ??