A study reported on the effects of vitamin c in breast milk for breast-feeding mothers. the children whose mothers had chosen to take high doses of vitamin c had a 30% lower risk of developing allergies. can you conclude that the use of vitamin c caused the reduction in allergies? why or why not?

No, you can not conclude Vitamin C use reduces allergies because this could be correlation, without causation. Mothers who used vitamin C may have qualities that decreased allergies, like lower smoking rates or improved pre-natal care. There also needs to be a control group to validate the intervention data.