Take a look at the passage again:
Anyone who enters Cedric's apartment can tell that this young man has a
dog. For example, puncture marks in the mini blinds, dog snot clouding the
windows, and paw prints on the beige upholstery.
You chose to connect the afterthought fragment to the main clause in front, like this:
Anyone who enters Cedric's apartment can tell that this young man has a
dog; for example: puncture marks in the
mini blinds, dog snot clouding the windows, and paw prints on the beige
upholstery.
Unfortunately, the version that you chose has too much elaborate punctuation. Review the rules.
Go back to the sentence to try again.