Final answer:
Butter and cheese are not primary sources of linolenic acid in the American diet.
Step-by-step explanation:
Linolenic acid is an omega-3 fatty acid found in certain food sources. The primary sources of linolenic acid in the American diet are flaxseeds, walnuts, salmon, sardines, soybean oil, and corn oil. However, butter and cheese are not primary sources of linolenic acid in the American diet.