A group of college students is participating in a memory study that involves performing the same task each day under different circumstances; however, as each day goes by, the students are obviously getting more comfortable with completing the task. Which threat to internal validity has confounded this study?

practice

Explanation:

Practice effects may sensitize individuals by making them more aware of the purposes of the research and may serve as a stimulus to change or it may ginger them to change and this will influence the results of the study.

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.

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the correct answer is :

{b.}   ( american workers lose job opportunities )

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    -sprinkles