Which item belongs to one of the five food groups in the usda's myplate food guidance system? a.  oatmeal cookieb.  milkc.  olive oild.  salt

It is milk, because according to the MyPlate guidelines you need to have one cup of dairy with your meal, which is milk.

That would have to be milk considering it is the basis for the dairy section on the USDA's MyPlate Food Guidance System. Hope that helped!