Read the following passage, then choose the correct answer to questions. 

Smoking causes lung cancer, which is the number one cancer among men. Ninety percent of the people who get lung cancer die. Smoking is also the leading cause of mouth cancer, tongue cancer, and throat cancer.Many smokers have heart disease and pneumonia. Smoking causes one million early deaths in the world every year.

Smokers not only harm themselves but also harm others. Smokers breathe smoke out into the air. They breathe it out on their children and their wives or husbands. Children whose parents smoke have more breathing and lung problems than other children. Women who are married to smokers are more likely to have lung cancer than those married to non-smokers.

We are all aware that smoking is bad. So why do people smoke?