The hands-off era is said to have ended in 1970 when a federal district court declared in the case the entire Arkansas prison system "so inhumane as to be a violation of the Eighth Amendment bar on cruel and unusual punishment."

Holt vs. Sarver

Explanation:

Based on the information provided within the question it can be said that the court case that is being pointed to in this scenario is the Holt vs. Sarver case. This was a court decision which would ultimately become the first of many cases where the court would find the entire state prison systems in violation of prisoners' constitutional rights with them being accused of  inflicting cruel and unusual punishment to the prisoners.

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.