Aresearcher finds that people who own more than two cars have bigger homes, more garage space, and make more money than people who own only one or two cars. therefore, the researcher concludes that having more than two cars causes people to have homes with bigger garages. according to cook and campbell's types of evidence, the researcher failed to eliminate:

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.

answer; substantive law;