More than 80% of the executives in the county attended high school in the county, and clearly they represent some of the brightest in the county. Among the seventeen high schools in the county, the three in the coastal towns have had the highest test scores in the county for several decades. A recent study shows that almost all of the county executives who attended high school in the county attended one of those three high schools in the coastal towns.
The argument above is most vulnerable to criticism on which grounds?
【选项】The argument assumes without basis that these county executives were above-average students at their respective high schools.