Review the map below. Which of the following resources is found in Canada and the United States but not Mexico?

The image shows various natural resources across North America. In Mexico, the map indicates copper, silver, and iron are found. Across the United States, iron, oil, coal, copper, and silver are found. In Canada, lead and zinc, coal, copper, oil, iron, gold, silver, and uranium are found. In Alaska, coal, gold, and oil are found.
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Copper
Oil
Silver
Iron