Results from a research study suggest that a stop-smoking program is very successful. however, the participants who volunteered for the study were all highly motivated to quit smoking and the researcher is concerned that the same results may not be obtained for smokers who are not as motivated. this study has a problem with

The correct answer is The study has a problem with the External validity

Explanation:

External validity in research terms is the validity the research has in the outside world or in the applied social reality of the field of study, it is the extent in which the results and conclusions of the study can be applied and generalized to ohter external factors, therefore in this case, when the researchers did the experiment only with motivated volunteers did not take into account that people outside may not have the same motivation, therefore the results may not be the same in the external social reality and thus having problems with the external validity.

idk but found this on google

"the kansas-nebraska act allowed each territory to decide the issue of slavery on the basis of popular sovereignty. kansas with slavery would violate the missouri compromise, which had kept the union from falling apart for the last thirty-four years. the missouri compromise had prevented this from happening since 1820."

b) the planets year length would be longer

hope this !