What's wrong with this?

Find what's wrong here...
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0
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Did you know that 80f Stanford students could not find the error above? Click Here to see if you were right or to get the correct answer.

I actually found the error, but I couldn't figure out how to put it into the drop down menu so it would say I got the right answer. The "O" is a zero in the list. Whoever wrote it needs to go back to basic English. When they give the correct answer they use "your" instead of "you're". Is it wrong that annoys me?