he variable age is a possible confounder in this study. Choose the best reason why. A variable is a confounder if, based on its value, it prohibits some members of the sample from participating in the study. For this study, there may be some people in the sample who have a birthday during the study. Thus, their age would change during the study, making it not possible for them to participate. A variable is a confounder if its effect on the outcome cannot be distinguished from the effect on the outcome from different treatments. (In our context, the outcome is yearly income, and the treatments are needing corrective lenses and not needing corrective lenses.) There is already a noticeable difference between the two groups of participants in terms of wearing corrective lenses. It's possible the participants in the corrective lenses group differ from the participants in the no corrective lenses group in other characteristics, such as age, making it difficult to determine which variable is affecting yearly income