Fact 1: Smoking tobacco decreases stamina. Fact 2: Tobacco is grown for cigarette factories. Given the two facts above, smoking cigarettes will do what?

OPTIONS: 1). increase lung capacity. 2). increase stamina. 3). Abnormal cell growth. 4). kill them. 5). hyperthyroidism. 6). harmful substances. 7). decrease stamina. 8). decrease health problems.
The answer is:
7).