53.
Your Answer is
Correct Answer is B
Explanation
Each is used as an apposition to further explain doors, and B is correct.
Item A: The full stop is not a complete sentence, wrong.
Item C: in which leads the attributive clause, the antecedent department cannot be an adverbial in the clause, and the semantics are wrong.
Item D: There is no parallel content before and after the cause of the error.