Which is the best topic sentence for a paragraph within a paper?

more and more people are quitting smoking because it increases the risk of lung cancer.

the main reasons people are quitting smoking are that it increases the risk of lung cancer, it's offensive to others, and it's very expensive.

one way to save on monthly bills is to quit smoking, and quitting can also your social life by making you more pleasant to be around.

smoking is a major health epidemic in the united states because it endangers the physical, emotional, and social well-being of smokers, those with whom they regularly interact, and the general public.