This is an observational study and the conclusion of the researcher is not justified.
A controlled experiment is such that all the other factors in the experiment are kept the same except the variable that is being studied. This study is not a controlled experiment is not a controlled experiment because other factors that could affect the study were not carefully controlled.
This is an observational study. The conclusion of the researcher is not justified because other factors such as diet which could affect the blood pressure were not taken into account.
Learn more about controlled experiment: https://brainly.com/question/4444046