What is Daniel Boone known for? Finding gold
Fighting in the American Revolution
Exploring the frontier
Befriending the Native Americans

Daniel Boone was an early American frontiersman who gained fame for his hunting and trailblazing expeditions through the Cumberland Gap, a natural pass through the Appalachian Mountains of Virginia, Tennessee and Kentucky.

Among the first Native Americans to take part in the Revolutionary War actually joined the rebel side. ... Other Native Americans joined the British side and fought to defeat the American invasion of Canada in 1775-1776. Native communities did not always make unanimous decisions about which side to support.

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.