The harmful effects of tobacco use are mainly caused by what substances?
nicotine, tar, carbon dioxide
nicotine, tar, carbon monoxide
opium, alcohol, carbon monoxide
nicotine, alveoli, carbon

Nicotine, tar, and carbon monoxide are substances that cause harmful effects in tobacco use. There are actually 4,000 different chemicals found in cigarettes and 43 of which are known to cause cancers. Some 400 chemicals contain toxins that the body cannot properly ingest or absorb. Other chemicals like formaldehyde, ammonia, hydrogen cyanide, arsenic, and DDT nicotine have a highly addictive nature which make people dependent on tobacco use.

Obviously smoking is not good for the body and it is addicting. It is one of the leading causes of lung cancer in individuals around the world.

The answer would be a