Aresearcher wants to conduct a study to see if playing chess improves memory. the researcher finds 50 individuals who play chess regularly and 50 that do not. each of the 100 individuals are given a questionnaire designed to determine memory level. if the 100 individuals did not know they were participating in the study, which statement about the study is correct?
1. it is an experiment where playing chess is a blocking variable.2. it is a matched-pairs design.3. it is a randomized experiment.4. it is an observational study.5. it is a double-blind study.