With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The Matrix Revolutions is a film.
text_B: Commercial tobacco smoke is a mixture of more than 5000 chemicals .. According to the U.S. Department of Health and Human Services , the following are known human carcinogens found in cigarette smoke  :. U.S. Department of Health and Human Services. U.S. Department of Health and Human Services. carcinogens. carcinogens. cigarette smoke. cigarette smoke
not_related.