Scientists have found that the Uranium-235 content of an unknown prehistoric sample was reduced to one-fourth. What best describes the identity of the sample? (1 point)

A. (A stone artifact that formed 700 million years ago)

Explanation:

I just needed some points, but also thank the other guy here for being smart

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.

i'd have to with d.

explanation: