"In June of Year 1, Jake's wife, Darla, died. The couple did not have any children and Jake did not remarry in Year 1 or Year 2. Which is the most favorable filing status for Jake in Year 2"

Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?