Directions: Find out whether there is an error in the highlighted parts. The error, if any, will be in one part. If there is no error, the answer is (5). Ignore errors of punctuation, if any.

This enormously building has many emergency exits and secret chambers on every floor. One can even get lost in it. To some, it appears as a maze. The first time when we took the tour of the building, we had the blueprint in our hands.