Here's a quiz to challenge even the most devout music fan. Following are 15 of the biggest-selling albums in music history. In fact, all of these have sold at least 10 million copies in the United States alone.

The trick? We've left some of the covers as they originally were, but altered others by reversing the photos or images on them. Your goal is to identify which ones are "kosher" and which are "bogus."

Good luck!

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