How did the Bubonic Plague affect the lives of serfs in Medieval Europe?

It has been argued that the Black Death brought about the end of feudalism. This was the system of service in return for a grant of land, burdening the peasant with many obligations to his lord. ... Lords and peasants alike were indicted for taking higher wages. In 1363 a Sumptuary Law was brought through parliament.

the Bubonic Plaque is also known as the black death

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.