Supply is the amount of a good or service that producers are willing and able to provide at various prices during a specified time.

True that is the correct definition of supply. Demand is what the name suggest it Is the demand or need for a material or merchandise. Supply is the ability to meet the demand or the defintion you just described. Supply and demand is what makes things that should be cheap expensive and the expensive things cheap.

Explanation:

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.

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