（辨认主题句）Choose the best topic sentence from the four options belo

（辨认主题句）Choose the best topic sentence from the four options below.Write the corresponding letter of your choice in the blank provided.

Your choice:
A、Passive smokers may easily catch the diseases active smokers invite.
B、Passive smoking is becoming widely recognized as a major health hazard.
C、Researchers find that second-hand smoke increases one’s risk of lung cancer.
E、Passive smoking refers to the second-hand smoke that nonsmokers breathe in.
【正确答案】：B