Fact 1: Lung cancer is most often caused by exposure to tobacco smoke. Fact 2: Tobacco is smoked in pipes or in cigarettes or bidis. Given the two facts above, what is lung cancer most often caused by?
OPT: (1). the Moon; (2). Pollution; (3). sunlight; (4). Chemical energy; (5). fossil fuels; (6). cigarettes; (7). burning; (8). marijuana smoke;
Answer:
(6).