b)The variable number of times the woman has given birth is not 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 were no women in the sample who had never given birth. So, each woman in the sample could participate since they could be placed into one of the two groups. 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 birth weight, and the treatments are smoking and not smoking.) In this study, both treatment groups (smoking and nonsmoking) were similarly comprised of only women who had given birth for the first time. Thus, the researcher designed the study so that the number of times the woman had given birth would not be a confounder