Activists sometimes advocate living "off the grid," which, in its simplest form, means living without buying electricity and water from utility companies. However, they also admit that living off the grid is getting harder and harder, because there simply isn’t enough affordable land in places where it would be feasible to do so. This means that most Americans have to:

Deal with bureaucracies.

a is the answer because it just is

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.