A. The teachers room is clean.
B. The teacher's room is clean.
C. The teachers' room is clean.
D. The teachers room's clean.
Answer: The teacher's room is clean.
A. The teachers room is clean.
B. The teacher's room is clean.
C. The teachers' room is clean.
D. The teachers room's clean.
Answer: The teacher's room is clean.
Additional Information: The apostrophe indicates possession.
Subjects: Punctuation, Grammar