Please answer the following question: Read the article and select the best answer. Article: Why do people smoke? One reason is that people become addicted to cigarettes. The addictive substance in cigarettes is nicotine . When people smoke, the nicotine goes right into the blood stream and makes people feel comfortable. A smoker's body gets used to the nicotine, and if he stops smoking, he feels nervous. Many smokers try to stop smoking but because of the addiction to nicotine they feel so uncomfortable that they often find it too difficult _ . Another reason is that people simply enjoy smoking. Having a cigarette for many people means taking a break. For some people smoking becomes part of certain social rituals , for example, sending the cigarette after dinner. Many people enjoy smoking because it gives them something to do with their hands. Reaching for a cigarette, lighting it and flicking the ashes are special comfort in a situation where they feel nervous. Many people also like the taste of tar in cigarettes. However, it is the tar that causes cancer. While governments and health experts have tried to get people to give up smoking completely, cigarette manufacturers have tried to keep selling them by producing cigarettes with less tar. Many people in western countries have welcomed these cigarettes since they found it hard to stop smoking and wanted to reduce the danger to their health. Question: According to the passage, what gets people into the habit of smoking? Options: A: The cigarette. B: Nicotine. C: Tar. D: Blood.
A:
B