Answer:
(B.) The main reason people are quitting smoking are that it increases the risk of lung cancer, its offensive to others and it's very expensive
Step-by-step explanation:
Found in the introductory paragraph, a thesis statement establishes the main ideas, points or elements that are going to be discussed and analyzed in an essay or article's body paragraphs.
Option B is the best thesis statement because it presents concise and specific information that can be thoroughly discussed in three paragraphs, which illustrate the essay's main topic: reasons why people are quitting smoking.
The remaining options are not good thesis statements because they do not offer multiple and specific ideas considerable for an analysis or discussion.