A new study suggests that if pregnant women receive too little sun exposure during the first trimester of pregnancy, children born may have an increased chance of developing multiple sclerosis in the future, due to lower vitamin D levels in the body and multiple sclerosis Associated with an increased risk of illness. Which of the following, if true, would most weaken the above conclusions? ["In addition to sunlight, you can also increase the body's vitamin D content through a variety of foods.", 'Newborns with lower levels of vitamin D are more likely to develop multiple sclerosis.', 'Pregnant women are underexposed and their fetal central nervous system may be affected.', 'The content of vitamin D in the fetus depends on the content of vitamin D in the mother.']