(c) the variable nutritional habits of the mo...

(c) the variable nutritional habits of the mother is a possible confounder in this study. choose the best reason why.\n○ 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 women who had extremely poor nutritional habits making them unable to give birth. so, it is possible that some women in the sample could not participate.\n○ 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 exercising and not exercising.) there is already a noticeable difference between the two groups of women in terms of exercise habits. its possible the women in the exercising group differ from the women in the not exercising group in other characteristics, such as nutritional habits, making it difficult to determine which variable is affecting birth weight.

Answer

# Brief Explanations: A confounder is a variable that affects both the exposure (exercise habits) and the outcome (birth - weight). The second option correctly states that the effect of nutritional habits on birth - weight cannot be distinguished from the effect of exercise on birth - weight, as women in the exercising and non - exercising groups may differ in nutritional habits. The first option incorrectly defines a confounder as a variable that prohibits sample participation. # Answer: 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 exercising and not exercising.) There is already a noticeable difference between the two groups of women in terms of exercise habits. It's possible the women in the exercising group differ from the women in the not exercising group in other characteristics, such as nutritional habits, making it difficult to determine which variable is affecting birth weight.