In the U. S. free enterprise system, property rights give owners the right to: A. store their property on public land at no cost.
B. sell their property without paying taxes.
C. freely sell their property to make money.
D. disregard legal regulations on their own property.

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.