what are the three main ingredients in cigarettes?
['Nicotine (the addictive drug that produces the effect people are looking for and one of the harshest chemicals in tobacco smoke)', 'Hydrogen cyanide.', 'Formaldehyde.', 'Lead.', 'Arsenic.', 'Ammonia.', 'Radioactive elements, such as uranium (see below)', 'Benzene.']