Directions: The following question tests your ability to recognize grammar and usage errors. The sentence contains either a single error or no error at all. No sentence contains more than one error. The error, if there is one, is underlined and lettered. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence is correct, select choice (E). In choosing answers follow the requirements of standard written English.

The door (A) is locked (B) from inside; someone (C) must have been (D) inside the room. (E) No error